euphemism

1650s, from Greek euphemismos "use of a favorable word in place of an inauspicious one," from euphemizein "speak with fair words, use words of good omen," from eu- "good" (see eu-) + pheme "speaking," from phanai "speak" (see fame (n.)).

In ancient Greece, the superstitious avoidance of words of ill-omen during religious ceremonies, or substitutions such as Eumenides "the Gracious Ones" for the Furies (see also Euxine). In English, a rhetorical term at first; broader sense of "choosing a less distasteful word or phrase than the one meant" is first attested 1793. Related: Euphemistic; euphemistically.

An agreeable word or expression substituted for one that is potentially offensive, often having to do with bodily functions, sex, or death; for example, rest room for toilet, lady of the evening for prostitute. The Nazis used euphemism in referring to their plan to murder the world's Jews (see also Jews) as “the Final Solution.”