The noun euphemism means using pleasant words or expressions to refer to things which people find offensive or embarrassing to talk about.

Synonyms are grandiloquence, circumlocution, purism, or pretense.

The word origins from Greek (1650s) euphemismos meaning “use of a favorable word in place of an inauspicious one, superstitious avoidance of words of ill-omen during religious ceremonies”. This is from euphemizein meaning “speak with fair words, use words of good omen”. It comes from eu– meaning “good, well” plus pheme meaning “speech, voice, utterance, a speaking”, from phanai meaning “speak”.

Euphemism is commonly used as a figure of speech.

I’m not impressed by his coy euphemism.

That term was used as an euphemism for the death of his old comrade.