An Etymological Dictionary of Astronomy and Astrophysics

An inoffensive word or phrase substituted for one considered offensive or hurtful, especially one concerned with religion, sex, death, or excreta (TheFreeDictionary.com).

Etymology (EN): From Gk. euphemismos, from euphemizein “speak with fair words, use words of good omen,” from → eu- “well,” + pheme “speech, voice, talk,” from phanai “to speak,” ultimately from PIE *bha-
“to speak, tell, say;” cf. Skt. bhanati “speaks;” L. fari “to say,” fabula “tale, story,” fama “talk, rumor, report; reputation;” Armenian ban, bay “word, term.”

Etymology (PE): Xošguyi, xošzabâni, literally “pleasant talking, ~ speach,” from xoš “well, pleasant,” → eu- + guyi verbal noun of goftan “to say, talk, speak,” → logic; zabâni, from zabân, → language.