"special right or privilege granted to someone," late 14c. (in Anglo-Latin from late 13c.), from Old French prerogative (14c.), Medieval Latin prerogativa "special right," from Latin praerogativa "prerogative, previous choice or election," originally (with tribus, centuria) "unit of 100 voters who by lot voted first in the Roman comita," noun use of fem. of praerogativus (adj.) "chosen to vote first," from praerogere "ask before others," from prae "before" (see pre-) + rogare "to ask, ask a favor," apparently a figurative use of a PIE verb meaning literally "to stretch out (the hand)," from root *reg- "move in a straight line."