v.intr. 1 (often foll. by against, over) be victorious or gain mastery. 2 be the more usual or predominant. 3 exist or occur in general use or experience; be current. 4 (foll. by on, upon) persuade. prevailing wind the wind that most frequently occurs at a place. prevailingly adv.
[ ME f. L praevalere (as PRAE-, valere have power), infl. by AVAIL ]