Idiom
Idioms had phrasing that had figurative meaning often unrelated to the actual phrasing. By studying the etymology of an idiom, one could determine how it came to be used. ()

The Leyron were known to communicate using gestural idioms. ()

Artistic, economic, military, and nautical terms, as well as sports sayings often contained idioms.

Popular idioms

Bad taste in (someone's) mouth 
Something that tastes so bad that it may cause nausea. (; )
 When the dikironium cloud creature, a cloud creature that fed on iron-based hemoglobin, attacked Spock, whose hemoglobin was copper-based, the result left its victim unscathed. Doctor Leonard McCoy observed that due to this fact, "I'll bet he left a bad taste in the creature's mouth, too." Spock replied that his comment was "Colloquially expressed, but essentially correct." ()

Between a rock and a hard place 
Referred to someone who was in a situation where they could choose between two alternatives, and neither of them were acceptable.

In 1986, Bob Briggs told Gillian Taylor, they were in such a position regarding the fate of George and Gracie, explaining "If we can't keep them here without risking their lives. We can't let them go without a taking the same chance." ()

Bird in a gilded cage 
To be a bird in a gilded cage was to live in luxury without freedom. 

In 2268, Kirk described the crew of the  on the planet Mudd as birds in a gilded cage and asked how they could escape, to which Pavel Chekov replied that he had no ideas but that it was a very nice gilded cage. Kirk reminded everyone that despite it containing their deepest desires, it was a cage nonetheless and that they belonged back on the Enterprise. ()

Black and white 
To be "black and white" was for something to be either one thing or another, with no in between. The term was also related to another idiom, "cut and dry", and was the opposite of "a shade of gray".

 When Korob approached Spock on his way of thinking, in 2368, he stated to the Vulcan that "There are no colors to your patterns of logic. There's only black and white." ()
 Due to Tom Paris' interest in history, he noted to Kathryn Janeway that he had "been studying how past generations viewed the future." Concluding that "it didn't work out quite as black and white as they imagined." ()

(A) black cloud hanging over your head  
A black cloud or dark cloud was an indication of a gloomy day, and anyone associated with a black cloud, especially one hanging over someone's head, was said to be having a bad day.

"It's like this big, black cloud with lots of thunder and lightning all around us."
 A simile used by Corin to explain to Tuvok what her fear would look like in a physical form. ()

"Just follow the black cloud" 
 Quark about how to locate Odo, who he described as "one depressed ex-Changeling." () 

"The only dark cloud I see around here is you." 
 Jadzia Dax to Worf while visiting Risa in 2373. ()

"A black cloud hanging over (your) head"
 While conferring with B'Elanna Torres about her Day of Honor, Neelix offered a suggestion, without knowing why such a cloud hung over Torres' head, he offered to be her "pressure valve". ()

Bloody nose 
When used idiomatically, a "bloody nose" meant a minor inconvenience.

After Q introduced to Borg to Picard and his crew, he said that "If you can't take a little bloody nose, maybe you ought to go back home and crawl under your bed." ()

Break the ice 
To "break the ice" meant to introduce conversation or small talk into an awkward situation.
 In 2151, Captain Jonathan Archer called a planned dinner with Vulcan Captain Vanik, he described the event as a "good way to break the ice." ()
 In 2371, The Doctor changed his program so that he would no longer say "Please state the nature of the medical emergency" when activated. When Kes discovered that he changed it back, and asked why, The Doctor explained that "I became so uncomfortable trying to find new ways to break the ice, as it were, that I restored it. Let's just say it works for me." ()

Burning the midnight oil 
Referred to what one did when they stayed up late at night to work or study. ()

In 2143, A.G. Robinson, who got to be the first Human to test the NX-Alpha test vehicle, told Jonathan Archer that he didn't get this assignment because he tried too hard, "burning the midnight oil" in the simulator eighteen to twenty hours a day. ()

In 2376, Captain Kathryn Janeway, who was working very late one night in the mess hall, told Neelix that she was "just burning the midnight oil", to which Neelix replied that it was way past midnight. ()

In an alternate timeline in 2364, Captain Jean-Luc Picard ordered Miles O'Brien to bypass the secondary plasma inducer, which required O'Brien to realign the entire power grid, stating "we're all going to be burning the midnight oil on this one." Data, who overheard O'Brien, told him that that would be inadvisable because any "attempt to ignite a petroleum product on this ship at 0:00 hours [would] activate the fire supression system." ()

Can't see the forest for the trees 
Referred to one was so caught up in small details that they were not able to see the bigger picture.

In 2373, Miles O'Brien felt he hadn't been able to see the forest for the trees when it was Rom who explained to him that the modifications that he had been making to equipment on Deep Space 9 on the orders of a Pah-wraith that had possessed his wife were designed to turn the station into a chroniton array aimed at the Bajoran wormhole, one which could kill the Prophets. ()

Casting a pall over  
Referred to creating a somber mood in an otherwise pleasant situation.

In 2371, Julian Bashir apologized for casting a pall over a party when his thoughts were still on Bareil Antos's medical condition. ()

Cat and mouse  
In 2267, Spock described Trelane's repositioning of the planet Gothos so that it was always in front of the 's flight path as a "cat-and-mouse game," Kirk adding that they were the mouse. () / (; ; )

When Dr. McCoy was on a planet where people's thoughts were made into reality via robots, he described the malevolent robots chasing them as "cat and mouse". This caused a large, aggressive, robot cat to appear.

Caught with one's pants down 
Referring to being found in the act of doing something which left one in an embarrassing position.

In 2285, James T. Kirk characterized his having been trapped by Khan Noonien Singh as having been caught with his britches down, a fact he attributed to his own supposed senility. (In 2366, Geordi La Forge opined that Romulan defector Alidar Jarok was correct a

bout Romulan activity at Nelvana III, and that the Romulans would indeed be caught with their pants down. Data, unfamiliar with the phrase, questioned what he meant, and La Forge explained. ()

Caught with one's hand in the cookie jar 
Referring to being or accessing something that was not one's own. 

In 2151,  had Hoshi Sato decrypt a message from the Vulcans and found it was a personal letter meant for T'Pol. When expressing his embarrassment at having inadvertently snooped on her private business, he said that he felt as though he had been caught with his hand in the cookie jar. ()

Chasing ghosts
To "chase ghosts" meant to pursue an imaginary threat, or to pursue someone despite them being dead.

When Hengist was opposed to allowing Scotty to investigate three murders of which he was the prime suspect, but which new evidence suggested were committed by a non-corporeal lifeforms, he expressed disapproval at allowing Scotty to "go and start chasing ghosts". ()

When the Sheliak asked the crew of the Enterprise-D to remove the humans from Tau Cygna V and Riker noted that the planet contained hyperonic radiation, which was deadly to humans, he said, "Then the Sheliak are asking us to chase ghosts?" ()

Clean as a whistle 
Referred to something being completely clean.

In 2369, retracing the murdered Ensign Aquino's steps, Chief O'Brien found that Runabout Pad C was as clean as a whistle. ()

In 2374, The Doctor told B'Elanna Torres that her pericardium was as clean as a whistle, having repaired injuries caused by Dejaren.  He was not able to say the same about sickbay's condition after a day in Tom Paris' charge. ()

Clean their chronometers 
Colonel West, while proposing Operation Retrieve, assured the Federation President that should the operation precipitate a full-scale war with the Klingon Empire, Starfleet could quite frankly "clean their chronometers." ()

Cold-blooded 
The term cold-blooded, in addition to its informal scientific meaning, was also applied to an individual who lacked emotion or was deliberately callous. 

When Captain Jean-Luc Picard sheepishly approached Doctor Beverly Crusher following her arrival onboard the  to apologize for his conduct on the bridge when welcoming her aboard, he emphasized that "I didn't want you thinking me harsh. Cold-blooded." When asked why she would ever think that, he explained that, "I didn't welcome you aboard personally, professionally. I made you come to me on the bridge. I yelled at your son. Who, as you pointed out, was quite correct." ()

When the USS Enterprise-D struck a quantum filament in 2368, and the ship was under the threat of a containment breach, Ensign Ro Laren suggested that should separate the saucer and get as far as they could from the drive section. Chief Miles O'Brien, however, felt that her suggestion was "damn cold-blooded," leaving all of those people in that section behind. Ro argued that ""there's no evidence that anyone is still alive in the drive section," but O'Brien argued back that, there was "no evidence they're dead, either. If you were trapped down there, would you like us to just cut you loose and leave?" ()

During Gul Dukat's questioning of Captain Benjamin Sisko if he was among those that supported the post-Bajoran Occupation vilification, Sisko diplomatically replied, "I wasn't there during the occupation. I didn't see all the things you had to struggle with day after day. I don't think I can pass judgement." However, a hallucination of Kira Nerys told Dukat that, "he's just doesn't want to anger you. He really thinks you're a vicious, cold-blooded killer, Dukat, and so do I." ()

Dining on ashes 
"Dining on ashes" was to excessively focus on past personal failures.

James Kirk asked if Spock was dining on ashes after finding him seemingly reflecting on the betrayal of Valeris. ()

Dry spell 
A "dry spell" was a prolonged period without sexual activity. 

After learning that Vulcans only mated once in seven years,  remarked that that was "a hell of a dry spell." ()

A dry spell could also be a synonym for a drought. When Kathryn Janeway was a child, a character on a holonovel she was using predicted a "dry spell" (as in a drought), so Janeway diverted a river. This backfired when it caused a flood and attracted a large mosquito named . ()

Everything but the kitchen sink 
"Everything but the kitchen sink", meant that almost everything possible was being used to make something work, or likewise present in a single location.

When the  was caught in Vaal's tractor beam, Montgomery Scott was "putting everything but the kitchen sink into impulse power" just to keep the ship from being pulled out of orbit. ()

While trapped inside a graviton ellipse, Commander Chakotay took note of the variety of debris contained within, describing "asteroid fragments, pieces of vessels, matter from every quadrant of the galaxy. Next time I lose something I'll know where to look. Instead of a graviton ellipse we should call it the "kitchen sink" anomaly." ()

Falling on deaf ears 
"Falling on deaf ears" meant something that some believe should be heeded was not.

In 2369, Captain Picard told Dr. Crusher that the discovery made from Professor 's research would have been more fitting to Galen's legacy if only it "had not fallen on such deaf ears." ()

Weyoun once told Major Kira that her pleas to have Rom not executed for terrorism would fall on deaf ears. ()

In 2372, Neelix believed diplomatic negotiation with the Botha might fall on deaf ears. ()

In 2374, The Doctor complained that his requests for a larger sickbay were falling on deaf ears. ()

Fly on the wall
A "fly on the wall" or "spider under the table" was a colloquial way of referring to an observer.

When Sito Jaxa was wondering why the senior officers were going to the Federation-Cardassian border, she wanted to have been a "spider under the table" during the briefing. She asked Sam Lavelle if he felt the same way, to which he responded, "Is that like a fly on the wall?".  When Sito affirmed, he agreed. ()

For all the tea in China 
"For all the tea in China" meant something was so important to a person, he or she wouldn't exchange it for even the most precious things in the world.

In 1986, Gillian Taylor told time traveler Admiral James Kirk, when he explained to her that they wanted to bring George and Gracie to the 23rd century, and asked her if she was curious about the details, she said, "I wouldn't miss it for all the tea in China." ()

(A) genie from the bottle  
"A genie from the bottle" meant getting what one wanted, but with bad results.

 In 2154, Phlox used the cautionary Earth tale about the dangers of releasing a genie from the bottle to warn T'Pol that she may have to live with the emotions she was left with after ingesting trellium-D. ()
 In 2268, Spock told Cyrano Jones that by removing tribbles from their natural habitat, he had figuratively "removed the cork from the bottle and allowed the genie to escape." ()
 In 2372, Kathryn Janeway believed there would be no way to "put the genie back in the bottle", after the warp 10 barrier was broken. ()
 See also: Aladdin's lamp

Have the hide of 
To have the hide of someone was to chastise someone severely.

In 2269, according to Dickerson, Captain Kirk promised to have the hide of the first man to smile or otherwise react with amusement to the appearance of President Abraham Lincoln on the Enterprise. ()

Home sweet home 
 ; ; ;

I am who I am 
According to Tuvok, along with this saying, "It is impossible for me to be more or less like myself." ()

I couldn't fill your shoes 
"I couldn't fill your shoes" was a Human idiom, describing one being in a bad situation, which the other person couldn't bear.

In 2286, Leonard McCoy told Spock, when he suffered from memory loss after being resurrected, "What I mean is I may have carried your soul, but I sure couldn't fill your shoes," to which Spock replied, "My shoes?" ()

Iota 
An indication of a very small, indefinite measurement. (; )

Joined at the hip 
This term referred to people being so close to one another as to appear inseparable (physically or emotionally)

In 2369, Q described himself and Vash as "A team, joined together at the hip." ()

After being temporarily telepathically linked with Jean-Luc Picard on Kesprytt III in 2370, Beverly Crusher remarked that she was happy not to be joined to Picard's hip anymore. ()

In an alternate 2390, Harry Kim called Chakotay and his girlfriend Tessa Omond as close as to be joined at the hip. ()

Keep it under your hat 
To keep information under one's hat was to remember it for future reference.

 After Kasidy Yates told the Niners why Benjamin Sisko disliked , after promising to him she wouldn't tell, she told them "so you have to keep this under your hats." ()
 Upon learning that Quark was aware that Odo was ill, Miles O'Brien requested that Quark keep that information under his hat. ()

Kill two birds with one stone 
To kill two birds with one stone meant to accomplish two things at once.

When locked in the cargo bay with Beverly Crusher and dealing with a volatile substance that was leaking, Geordi La Forge noted that his idea was unconventional, but might serve to "kill two birds with one stone". ()

Make heads or tails of 
To make heads or tails of meant to understand something.

On October 23 2032, John Kelly couldn’t make heads or tails of a spacecraft he encountered within a graviton ellipse. ()

In 2151,  couldn’t make heads or tails of most of a transmission that had been intercepted aboard . ()

In November that year, Malcolm Reed couldn’t see head nor tails of Enterprise in an asteroid field the ship was supposed to be mapping. ()

In  2153, Reed had trouble making heads or tails of biometric data gathered by the A-6 excavation team. ()

While back in 2268, Miles O'Brien couldn’t make heads nor tails of the 's systems. ()

In 2364, Jean-Luc Picard asked Geordi La Forge how he could make head or tail of the jumble of images picked up by his VISOR. ()

In 2369, the  crew couldn’t make heads or tails of Professor ’s data. ()

Later that year, Thomas Riker believed as a result of reconfiguring the computer on Nervala IV several times, the Enterprise crew wouldn’t be able to make heads or tails of it. ()

In 2371, the computer aboard Deep Space 9 couldn’t make heads or tails of a ketracel-white repository. ()

Also that year, The Doctor couldn’t make heads or tails of an injured Kazon’s injuries. ()

In 2373, O'Brien couldn’t make head nor tail of the power relay systems on Japar's Bird-of-Prey. ()

In 2375, a medical tricorder couldn’t make heads or tails of a cytoplasmic lifeform’s unusual physiology. ()

Later that year, Harry Kim couldn’t make heads or tails of the contents of chaotic space due to the shifting readings. ()

Also that year, B'Elanna Torres couldn’t make heads or tails of the ’s injector manifold. ()

May God have mercy upon your soul
"May God have mercy upon your soul" was a phrase used in some ancient Earth cultures upon sentencing a person to execution. It was used in that capacity during Worf's 2371 promotion ceremony, which included holodeck roleplaying on a  and involved him walking the plank. () 

Q, immediately before adjourning his trial of humanity, said to Captain Picard "May whatever god you believe in have mercy on your soul!", a variant of this phrase. ()

Another variant of the phrase, "May God have mercy on our souls," was used by Malcolm Reed to end his final log entry when stranded in  and he believed there was no chance of rescue. ()

Media circus
A media circus was a Human idiom which described a news event where the coverage was out of proportion to the event itself.

In 1986, Gillian Taylor described to James T. Kirk the farewell ceremony for George and Gracie as a potential media circus. ()

Mind the store
Mind the store meant to be in charge in the absense of others. 

In 2266, upon contacting the Enterprise while stranded in command of a landing party on planet Alfa 177, Hikaru Sulu was surprised that the member of the crew who answered was none other than the starship's commanding officer, Captain James T. Kirk. He humorously replied that he was "watching the store," having given everyone else the afternoon off. ()

The next year, Kirk again referred to the Enterprises store, immediately after Doctor Leonard McCoy remarked that Spock reacting uncharacteristically overjoyed at finding that Kirk was still alive had been logical "in a pig's eye." To McCoy's comment, Kirk, momentarily turning back as he and Spock were about to leave sickbay, suggested they "go mind the store." ()

My mind's turned to clay
This expression, which meant that he was having trouble thinking, was used by Geordi La Forge in the running up to the battle of Wolf 359. ()

Needle in a haystack
"Needle in a haystack" was a Human idiom which described the long-lasting search for something in a large variety of possibilities.

In 2267, when searching for the , James Kirk remarked to High Commissioner , "Finding a needle in a haystack would be child's play." ()

In 2364, William Riker described searching Starfleet records for an instance of someone showering in their clothes as "like looking for a needle in a haystack." ()

In 2369 while searching for the crash landed runabout  in the Gamma Quadrant, Miles O'Brien compared the search with searching for a "bloody needle in a haystack." O'Brien and Jadzia Dax had to search several planets, two dozen moons, and an asteroid belt. ()

In 2370, a Paradan replicant of  commented "Needle in a haystack wouldn't do this job justice", describing the search for a fault in Deep Space 9's upper pylons. ()

In 2373, Jadzia Dax said to Benjamin Sisko "Do the words 'needle in a haystack' mean anything to you," after the  had spent two unsuccess days searching the Badlands for cloaked missiles appropriated by the Maquis for a strike against Cardassia. ()

On a silver platter
Referring to something that was offered to someone in a rather obvious manner.

In 2375, Neelix offered B'Elanna Torres the chance to insult his cooking by telling her to name her poison. After she missed that chance, he seemed disappointed, claiming he'd handed it to her on a silver platter. ()

One-way street
Meaning: The term referred to an agreement made by two parties, but only one party benefits from. 

When Captain James T. Kirk was explaining romantic relationships to Charlie Evans, he told him to take it slow, that it wasn't a "one-way street." ()

Over (my) dead body
Meaning: "You'll have to kill me to make that happen." Used to emphasize that a person's deep desire that something not occur. 
Captain John Christopher used the expression in 1969. ()
In 2366, Lwaxana Troi, who was being held hostage aboard the Krayton, pleaded with Captain Jean-Luc Picard that "The only way you'll ever get me back is over Tog's dead body!" ()
Major Kira Nerys used the expression in 2369. ()
Brunt used the expression in 2374. ()

Penny for your thoughts
"A penny for your thoughts" was a Human idiom, meaning that someone was curious about what the other person was thinking.

In 2368, Doctor Beverly Crusher used the expression when she wanted to get Jean-Luc Picard to talk to her during a conversation. When Picard asked her if she has one, she told him that the replicator probably has it on file. ()

In 2369, when Q brought back Picard to the incident at Starbase Earhart in 2327, he told him (acting as a bartender): "Penny for your thoughts? You never told me you were such a lady's man," also jokingly referring to Picard's unsuccessful date with Penny Muroc. ()

In 2370, Crusher used the expression again, dining with Picard, after they shared thoughts for a time via the psi-wave device on Kesprytt III. ()

In 2257, Amanda Grayson spoke of a similar idiom, "Isik for your thoughts," which she described as a Vulcan but was later revealed as something she heard her mother say. ()

In 2383, Zero used the expression after learning it from Hologram Janeway to talk with Gwyn about why she was feeling sad. ()

Play our cards right
Referring to "if things go well."
In 1986, Admiral Kirk used this metaphor when talking to Spock, leading Spock to ask "How will playing cards help?" ()

Play possum
Meaning: To feign death when an enemy approached.
In 2377, when Chakotay suggested the Hirogen might be laying a trap for Voyager, Kathryn Janeway dismissed the idea, saying that the Hirogen "aren't the type to play possum." ()

Playing twenty questions
Rather than playing an actual guessing game, this meant to make somebody ask questions rather than telling them directly what a problem or the answer was.

When Harry Kim claimed to be an American during the Hirogen simulation of World War II in 2374, Tom Paris became annoyed at the man's refusal to answer him, saying he didn't have time to play twenty questions. ()

Kathryn Janeway told Neelix the same thing when he was less than forthcoming about the delicate issue of non-functioning lavatories on  in 2375. ()

The powers that be
"The powers that be" was a phrase referring to a decision made by those in power, or the decision makers, without going into detail who those decision makers were (as it was not relevant to the story.)

In 2143, when Jonathan Archer and A.G. Robinson were attempting to take NX Alpha on a test flight, Archer informed A.G. of the good news that he had just gotten word from "the powers that be" that he was good to go for launch. ()

In 2256, Saru explained that he had been assigned to the  as first officer by "the powers that be" after the destruction of the . ()

Preaching to the choir 
"Preaching to the choir" was a phrase used to describe someone who was trying to convince another who was already a believer. 

In 2365, Phillipa Louvois told Bruce Maddox he was preaching to the choir when he attempted to explain the usefulness of having a Data aboard every starship. ()

Pull a rabbit out of (a) hat
Pulling a rabbit out of a hat was a type of magic trick. Metaphorically, it referred to performing any amazing feat.

In 2372, Julian Bashir said, "Next time I'm going to pull a rabbit out of his ear" ()

In 2373, Chakotay said, "What's your next trick, Harry. Pull a shuttlecraft out of a hat?" ()

In 2375, Ezri Dax, "Now we get to pull a rabbit out of our hat." ()

Later that year, Miles O'Brien said, "Julian, it's time to face facts. You're not going to pull a rabbit out of your medkit." ()

Pull the plug
To pull the plug meant to abruptly put a stop to something.

When the Vulcans were considering allowing Klaang to die rather than returning him to his people, since Klingons consider dying on duty to be an honour, Jonathan Archer expressed disdain at the Vulcans being willing to "pull the plug." ()

When Tuvok asked Janeway if she intended to allow a Borg fetus to mature, she replied that the only other alternative was to 'pull the plug' (i.e. terminate the fetus), which she was not willing to do. ()

When a vinculum was causing erratic behaviour in Seven of Nine, Janeway ordered B'Elanna Torres to pull the plug, i.e. destroy it. ()

Put me out to pasture
"Put (me) out to pasture" means to be forcibly retired. 

In 2287, Captain Kirk lamented that "When they put me out to pasture, I hope I fare better than Korrd." This after learning that the formerly great Klingon General whose military strategies were required learning at Starfleet Academy, to being posted at Nimbus III. ()

Rain on my parade
To rain on one (one's) parade was to spoil their fun.

In 2372, Dr. Julian Bashir, annoyed by Elim Garak's intruding upon his Julian Bashir, Secret Agent holo-novel program, told him that he could stay, but to keep quiet and not rain on his parade. ()

The real McCoy
"The real McCoy" described anything which was the genuine article in question, not merely a facsimile thereof.

In 2374, Vic Fontaine revealed to Odo that a new improved version of the "Lola Chrystal" hologram was in fact Kira Nerys, who the hologram's features were based on, and that the Changeling had been dancing with the real McCoy. ()

In 2375, "" classified Chakotay, unlike himself, to be "the real McCoy", (i.e. not a Species 8472 recreation of a Starfleet officer) and recommended "Valerie Archer" perform a genetic extraction in order to figure out a better way for members of Species 8472 to maintain a Human appearance. ()

Rich beyond the dreams of avarice
Doctor Leonard McCoy managed to convince Dr. Nichols to accept the formula for transparent aluminum as compensation for his services by saying that once he figured out the dynamics of the matrix (which would take years), he'd be rich beyond the dreams of avarice. ()

Run off at the mouth
An admission by Julian Bashir of something he tended to do that he confessed was "just a nervous habit." ()

Sauce for the goose
The Earth idiom "what's sauce for the goose, is sauce for the gander," was in part spoken by Spock following Saavik's notation that Khan Noonien Singh, aboard the  was following the  into the Mutara Nebula. In response, Spock stated "sauce for the goose, Mr. Saavik." ()

Shade of gray
To be or have a "shade of gray" meant to not be clear what was right or wrong, or good and evil, but instead existed in a gray area. The term was the opposite of what it mean to be black and white. 

Following Worf's transfer to Deep Space 9 in 2372, Captain Benjamin Sisko explained that "Starfleet officers often have trouble learning the unofficial rules of the station," as contrary to serving aboard the , Worf "always knew who were my allies and who were my enemies." Sisko reiterated the discussion, adding, "Let's just say DS9 has more shades of gray. And Quark definitely is a shade of gray. He has his own set of rules and he follows them diligently. Once you understand them, you understand Quark. I'd say that's true for everyone here." ()
After Captain Sisko's time in captivity with Gul Dukat, following the destruction of the , he explained to Jadzia Dax that he always thought "sometimes life seems so complicated. Nothing is truly good or truly evil. Everything seems to be a shade of gray." However, recalling his experience, he continued, "And then you spend some time with a man like Dukat and you realize that there is really such a thing as truly evil." ()

Short-sighted 
To be short-sighted described lack of imagination or foresight. Not to be confused with myopia.
In 2286, the Federation President told James T. Kirk he and the crew of the  had saved Earth from its own short-sightedness by bringing forward George and Gracie to deal with the Whale Probe. ().

In 2366, Admiral Alidar Jarok characterized Humans as a short-sighted people. ()

In 2369, Kira Nerys told Admiral Rollman she thought Benjamin Sisko was short-sighted in hesitating to allow Tahna Los political asylum. ()

Later that year, Gul Ocett told Nu'Daq he was remarkably short-sighted to believe he had surrendered his portion of an alien computer program for nothing when it emerged that the program was still incomplete. ()

In 2371, Elim Garak goaded Gul Dukat by claiming that Dukat's short-sightedness had held him back, and that Dukat's father had had the same problem. He later cited Dukat's own counter-insurgency program turning against him as evidence of this short-sightedness. ()

In 2372, Weyoun told Sisko he was being short-sighted in dismissing the projected takeover of the Dominion by a band of rogue Jem'Hadar as not being his, Sisko's, problem. ()

In 2375, Kathryn Janeway's reexamination of her decision to destroy the 's array four years previously, thereby stranding the  in the Delta Quadrant, led her to conclude that she had acted short-sightedly. ()

In 2376, Tuvok opined that it would have been short-sighted to destroy a graviton ellipse instead of studying it. ()

Sight for sore eyes 
Meaning: Something that was pleasing to look at.
In 2376, Harry Kim remarked that he would not want to bunk with the great explorers of the past. Tom Paris remarked that that would be a sight for sore eyes. ()
Shortly thereafter, after making contact with Voyager again, Lyndsay Ballard remarked that Captain Janeway was a sight for sore eyes. ()
Later that year, the con artist Dala used the expression sarcastically upon seeing Tuvok. ()

Someone walking on one's grave
To say that someone was walking on one's grave was to say that one felt strange.

When Kes felt unsettled, Janeway replied, "Someone was walking on your grave". Kes didn't know what the idiom meant, so Janeway explained, and Kes noted how morbid the saying was. ()

Stone knives and bearskins
"Stone knives and bearskins" was a colorful term employed by Spock to describe the 1930s technology he was forced to use to construct a tricorder interface. Vital information was locked within Spock's tricorder: How had Leonard McCoy changed history? Spock was eventually able to construct an appropriate circuit, but retrieved two separate recordings: one in which Edith Keeler lived, and one in which she died. At that point, the improvised interface erupted in sparks and flame, ruining his chance to learn which of the recordings represented McCoy's alteration, and which the correct timeline. ()

Kathryn Janeway also used this expression when typing on a late 20th century computer keyboard trying to find out information about Henry Starling. ()

Talk shop 
To talk shop was to discuss the rudiments of one's profession. 

In 2267, upon reconnecting with his ex-girlfriend Areel Shaw, James T. Kirk tried to discourage her from discussing his pending court martial, saying, "let's not talk shop". ()

That's life
"C'est la vie" (French: "that's life") was a Human idiom, meaning bad things happen, it was the way of life.

In 2285, when Admiral James Kirk self-destructed the USS Enterprise, killing most of Kruge's Klingon crew on board, he told the commander on the surface of the : "Sorry about your crew, but as we say on Earth, ...'c'est la vie." ()

Geordi La Forge once explained to Data that for the particular situation he was experiencing, it turned out that way, because "that's life". ()

Tip of the iceberg
Meaning: the first hint or revelation of something much larger or more complex. 
In 2153, Commander Charles Tucker called a Vissian Cogenitor's newly-gained ability to read the tip of the iceberg. ()

In 2373, Miles O'Brien tried to cover his tracks when he altered Deep Space 9's systems by telling Benjamin Sisko that it was hard to call that sabotage, since it didn't really pose a threat to the station. Sisko told him that the alterations "might be just the tip of a very large and dangerous iceberg." ()

The vultures are circling
To say that "the vultures [were] circling" was to state that many people wanted something, or that the speaker was being pursued by enemies.

When Voyager was being monitored by many ships while trapped inside an anomaly, Tom Paris noted that the vultures were circling. Janeway replied, "Vultures eat the dead, Mr. Paris. We're not dead yet." ()

When Janeway, Neelix, B'Elanna Torres, and Tuvok all wanted sirillium, Chakotay noted that the vultures were circling. ()

Walking on one's grave
If someone was walking on one's grave, that meant the person had a peculiar emotion or sensation.

When Kes noted a strange, sudden feeling of being "cold" and "shivery", Captain Janeway told her, "Someone was walking on your grave". The EMH was unfamiliar with this idiom, so Janeway defined it, to which he noted how macabre the idiom was. Janeway then expressed surprise that the EMH did not know the idiom since it originated on Earth, but he supposed that his programmers considered it unimportant. ()

Wash my hands of it
Meaning: to avert a wrong decision, claiming that the person could not be held responsible for it. 
In 2266, Doctor Simon Van Gelder accused Captain Kirk of escaping responsibility by taking him back to the Tantalus Colony, and told him, "You smart, button-pushing brass hat. Wash your hands of it. Is that your system? You're both quite sure of yourselves, aren't you?" ()
When the crew of the Enterprise-D accidentally killed a pregnant alien lifeform, Jean-luc Picard noted that it was their moral obligation to help deliver the infant lifeform, since they were responsible for its mother's death (albeit unintentionally) and it would be immoral for them to "wash their hands" of that fact. ()

The whole kit and caboodle
Referring to the entirety of something. 
In 2152, commenting that it was completely gone,  referred to a  from the 31st century and its contents as "the whole kit and caboodle". ()
In 2268, Montgomery Scott claimed to have transported "the whole kit and caboodle" of tribbles into the 's engine room. ()

Wild goose chase
Meaning: an expression used to mean futile pursuit or search after something.
In 2153, Jonathan Archer told T'Pol "Maybe we're just on a wild goose chase" after their initial attempts to locate a dark matter nebula failed. ()
In 2268, Leonard McCoy accused Spock of "run[ning] off on some wild goose chase halfway across the galaxy" when Kirk, Uhura, and Chekov disappeared from Gamma II. Spock replied, "Doctor, I am chasing the captain, Lieutenant Uhura, and Ensign Chekov, not some wild aquatic fowl." ()
Later that year, Spock described M-5 multitronic unit's diversionary tactics as "pursuing a wild goose." ()
After Katherine Pulaski was abducted by Professor  in 2365, Geordi La Forge believed she planned "to lead [Data] on a wild goose chase and then recount the story to everyone between here and Alpha Centauri." ()
In 2367, Data told Doctor Crusher that he "could be chasing an untamed ornithoid without a cause," describing this idiom, when examining the clues of Ambassador 's presumed death. Crusher eventually recognized the idiom, and corrected him with its common form. ()
In 2368, Jean-Luc Picard commented that the 's investigation of a Barolian freighter's activities at Galorndon Core "may prove to be a wild goose chase." ()
In 2369, Picard told Deanna Troi that his continuation of Professor 's research was not a case of his taking the Enterprise and its crew on a wild goose chase. ()
In 2371, Kira Nerys told Tom Riker that if she had hijacked the  as he had, she "wouldn't have gone flying off into the middle of Cardassia on some wild goose chase." ()
In 2372, Kathryn Janeway was concerned that investigating "Planet Hell" might prove to be a wild goose chase. ()

With one's name on it
Having one's name on something meant that the object in question belonged to or was reserved for them.

In 2372, Julian Bashir assured Odo that there was a Spitfire with his name on it in the hangar if he wanted to join the Battle of Britain holoprogram. Later, Joseph Sisko told his grandson there was a vat of crayfish that needed cleaning with his name on it. ()

In 2375, Miles O'Brien told Janel Tigan he was not looking forward to seeing Captain Sisko again, as he had a boot with O'Brien's name on it. ()

In 2377, Reginald Barclay offered Deanna Troi a drink. When she declined, he tried to tempt her, saying he had a chocolate passion punch with her name on it. ()

Within (arm's) reach 
For something to be "within arm's reach," or simply to be "within reach," meant for it to be very close or achievable. (; ) Contrarily, for something to be "(just) out of reach," meant for it to be very close, but unattainable. (; ; )

Jean-Luc Picard told Gul Macet that he knew that the Cardassian research station, located within arm's reach of three Federation sectors, was indeed a weapons depot, and that while recent events could have made things much worse than they already were, and that they should consider themselves warned. ()

Following 's discovery of the extremely dangerous, but deuterium-rich, Planet Hell, Ensign Harry Kim reminded the senior staff of the meek alternatives to the ship's low deuterium crisis, offering the idiom rich, "What's the alternative? Resume course? Creep along at quarter impulse hoping we find fuel before we end up dead in the water? We've got deuterium within arm's reach. We can't let the opportunity slip away without at least trying." ()

Work (one's) side of the street
To work (one's) side of the street was to take up another's line of work instead of one's own.

In 2266, after Kirk's successful handling of the situation with Harcourt Fenton Mudd, Eve McHuron, and Ben Childress, McCoy surmised Kirk must have talked them into rationality, asking if Kirk had ever thought of selling patent medicine. Kirk then quipped, "Why should I work your side of the street?" ()

See also 
Idioms

External links 

Linguistics
Philosophy
Literary devices
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