"depravity, infamy; shameful wickedness of character, inherent baseness or vileness," late 15c.,turpytude (Caxton), from Old Frenchturpitude (early 15c.), from Latinturpitudinem (nominativeturpitudo) "baseness," fromturpis "vile, foul, physically ugly, base, unsightly," figuratively "morally ugly, scandalous, shameful," a word of uncertain origin.

Klein suggests perhaps originally "what one turns away from" (compare Latintrepit "he turns"), but de Vaan finds proposed connections to IE words meaning "to turn" (via the notion of "to turn away") as "too constructed" to be credible.

Latinturpis also gave early Modern Englishturpify "make foul or filthy" (1580s), and Nashe usedturpie "ugly, filthy" inturpie lucre.