Palindrome (; "again") and ' (; "way, direction"). Palindromes date back at least to 79 AD, as a palindrome was found as a graffito at Herculaneum, a city buried by ash in that year. This palindrome, called the Sator Square, consists of a sentence written in Latin: "Sator Arepo Tenet Opera Rotas" ("The sower Arepo holds with effort the wheels"). It is remarkable for the fact that the first letters of each word form the first word, the second letters form the second word, and so forth. Hence, it can be arranged into a word square that reads in four different
Palindrome backward) is a name coined for words that spell a different word in reverse. The word was coined by [[Martin Gardner]] in his notes to [[C.C. Bombaugh]]'s book "[[Oddities and Curiosities of Words and Literature]]" in 1961. "Semordnilap" is itself a semordnilap. An example of this is the word "stressed", which is "desserts" spelled backward. "Noon" is a palindrome but not a semordnilap because it is the same word whether spelled backward or forward. Some semordnilaps are deliberate creations; an example in electronics (although rarely used now) is the [[mho]], a unit of electrical conductance, which is [[ohm]] spelled backwards,