sans-culotte (n.)

also sansculotte, "lower-class republican of the French Revolution," 1790, from French, literally "without breeches;" see sans + culottes. Usually explained as referring to the class whose distinctive costume was pantalons (long trousers) as opposed to the upper classes, which wore culottes (knee-breeches), but this is not certain. Related: Sans-culottes; sans-culotterie.