"annulling of (a law) by legislative action," 1530s, from Latin abrogationem (nominative abrogatio) "a repeal (of a law)," noun of action from past-participle stem of abrogare "annul, repeal," from ab "off, away from" (see ab-) + rogare "propose (a law), ask, request," apparently a figurative use of a PIE verb meaning literally "to stretch out (the hand)," from root *reg- "move in a straight line."
1580s, "sudden, unceremonious, without notice," a figurative use from Latin abruptus "broken off," also "precipitous, steep" (as a cliff), also "disconnected," past participle of abrumpere "break off," from ab "off, away from" (see ab-) + rumpere "to break," from a nasalized form of the PIE root *runp- "to snatch" (see corrupt (adj.)). The literal sense "broken off or appearing as if broken off" is from c. 1600 in English. Of writing, "having sudden transitions, lacking continuity," 1630s. Related: Abruptly; abruptness.