An ellipsis is an omission , a missing piece from something that is usually implied by the context.
Ellipses is the plural of ellipsis.
In writing we mark an ellipsis by three dots in a row "...
" For example: He was going to go to the store, but ...
An "ellipsis in thought" would be an omitted piece from someone's memory or chain of thought, which they can't remember but which they know is missing.
From the context, it sounds like the patient has suffered some kind of abuse which they have blocked out from memory, or suffers periods where they can't recall what happened.
ell.stackexchange.com/users/42184/Andrew
In writing, the ellipsis (not the ellipse , even though they both have the same plural form: ellipses ), which is represented by ... is used to indicate someone trailing off in the middle of a sentence, for example:
Well, I told him he needed to buy more printer paper...
Is that a squirrel over there?
In this case the psychiatrist was probably noticing the patient had trouble finishing sentences, or expressing whole ideas without losing their place and getting distracted.
ell.stackexchange.com/users/46361/mstorkson
An ellipsis generally describes a gap in something.
It could either mean a 'gap' in thought processes, for example:
I am going to the doctor tomorrow, therefore I must buy a toaster. at least to someone else, this would be confusing although in the speaker's mind it makes perfect sense.
Alternatively it could mean a complete loss of information, for example, the person couldn't remember certain aspects of an event.
The other more subtle meaning, that would only really become clear with more context would be that the 'ellipses in thought' were actually that the person was hiding something, and that they would trail off because they did not want to say what they were originally going to say.
ell.stackexchange.com/users/48426/Michael Curry
For all practical purposes English speaking persons should consider the medical term Ellipsis (plural form Ellipses) as a synonym to "lapse" : A mistake resulting from inattention A break or intermission in the occurrence of something A failure to maintain a higher state
Ellipsis originates from the greek word :
"ἕλλειψις" meaning want, deficiency, lack thereof, etc.
and although historically the Greeks used the same word for the mathematical shape which describes an ellipse, ellipse and ellipsis are two completely distinct words in English, carrying different meanings.
ell.stackexchange.com/users/48265/IfaacNewton
Sigmund Freud discusses " ellipsis of thought " in his case study A Case Of Obsessional Neurosis, especially the chapter Some General Characteristics Of Obsessional Structures . "
[N]amely,that of distortion by omission or ellipsis .
[...] For instance, the patients oldest obsessions ran as follows ' If I marry the lady, some misfortune will befall my father .' If we insert the intermediate steps, which are known to us from the analysis, we get the following train of thought: If my father were alive, he would be furious over my design of marrying the lady as he was in the scene in my childhood; so that I should fly into a rage with him once more and wish him every possible evil; and thanks to the omnipotence of my wishes these evils would be bound to come upon him
" (p106) as you can see the ellipsis appears "in a truncated and distorted form, like a mutilated telegraph" (p103)
Sigmund Freud, The Penguin Freud Library Volume 9; Case Histories II.
translated by James Strachey, Edited by Angela Richards.
Penguin Books, 1991
ell.stackexchange.com/users/84556/Eric Winnert
From Primal Fear (1996)A psychiater discovers that her patient suffers from the dissociated personality. She describes:   I kept seeing the signs. The big ones. Abusive background, these  repeated blackouts,  the ellipses in thought   I couldn't really understand what are ellipses in this case. All dictionaries say that an ellipse is from mathematics.
What does "ellipses in thought" mean?
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ell.stackexchange.com/users/37169/Dmitriy Esarev
An "ellipsis in thought" would be an  omitted  piece from someone's memory or chain of thought, which they can't remember but which they know is missing.  From the context, it sounds like the patient has suffered some kind of abuse which they have  blocked out  from memory, or suffers periods where they can't recall what happened. Alternatively it could mean a complete loss of information, for example, the person couldn't remember certain aspects of an event.   The other more subtle meaning, that would only really become clear with more context would be that the 'ellipses in thought' were actually that the person was hiding something, and that they would trail off because they did not want to say what they were originally going to say. An ellipsis is a gap, a missing piece, something omitted, so in this context it would be a piece of thought or memory that is missing, or that perhaps due to a traumatic event, the patient suffers from a loss of information/memory/periods that they have no idea what happened. Also, the psychiatrist might have noticed that the patient could not express full ideas/sentences without getting lost.  As a medical term, ellipsis means a mistake due to inattention/an intermission/the inability to maintain a higher state. Finally, it could also mean that the patient was withholding information and that is why they could not express concrete thoughts, but this interpretation needs more context to be accurate.
An ellipsis is a gap, a missing piece, something omitted, so in this context it would be a piece of thought or memory that is missing. As a medical term, ellipsis means a mistake due to inattention/an intermission/the inability to maintain a higher state. In this specific context, it could mean that perhaps due to a traumatic event, the patient suffers from a loss of information/memory/periods that they have no idea what happened. The psychiatrist might have noticed that the patient could not express full ideas/sentences without getting lost. A deeper meaning could be that the patient was withholding information and that is why they could not express concrete thoughts, but this interpretation needs more context to be accurate.