early 15c., derogacioun, "act of impairing an effect in whole or part," from Old French dérogacion (14c.) and directly from Latin derogationem (nominative derogatio) "a partial abrogation (of a law)," noun of action from past-participle stem of derogare "take away, detract from, diminish," from de "away" (see de-) + rogare "ask, question; propose," apparently a figurative use of a PIE verb meaning literally "to stretch out (the hand)," from root *reg- "move in a straight line."

From mid-15c. as "detraction, disparagement;" from 1510s as "act of impairing in merit, reputation, or honor."