"substitution of a vulgar or derogatory word or expression for a dignified or normal one," 1873, from Greek dys- "bad, abnormal, difficult" (see dys-) + phēmē "speech, voice, utterance, a speaking," from phanai "speak" (from PIE root *bha- (2) "to speak, tell, say"); Greek dysphemia meant "ill language, words of ill omen"). The opposite of euphemism. Rediscovered 1933 from French formation dysphémisme (1927, Carnoy).
The French psychologist Albert J. Carnoy gave an extensive definition in his study Le Science du Mot, which in translation runs: "Dysphemism is unpitying, brutal, mocking. It is also a reaction against pedantry, rigidity and pretentiousness, but also against nobility and dignity in language" (1927, xxii, 351). [Geoffrey L. Hughes, "An Encyclopedia of Swearing," 2006]