diatribe (n.)
1640s (in Latin form in English from 1580s), "discourse, critical dissertation," from French diatribe (15c.), from Latin diatriba "learned discussion," from Greek diatribe "employment, study," in Plato, "discourse," literally "a wearing away (of time)," from dia- "away" (see dia-) + tribein "to wear, rub," from PIE root *tere- (1) "to rub, turn." Sense of "invective" is 1804, apparently from French.