1911 Encyclopædia Britannica/Euphemism

EUPHEMISM (from Gr. εὔφημος, having a sound of good omen; εὖ, well, and φήμη, sound or voice), a figure of speech in which an unpleasant or coarse phrase is replaced by a softer or less offensive expression. A euphemism has sometimes a metaphorical sense, as in the substitution of the word “sleep” for “death.”