warm up intransitive verb Etymology:warm (II) + up 1.: to engage in exercise or practice especially immediately before entering a game or contest in order to limber up the muscles, work up speed, or get in condition < the pitcher was warming up with an overhand delivery — Dan Polier > 2.: to approach a state of or become characterized by violence, conflict, or danger < as the campaign warmed up … hired assassins had been brought in — H.H.Martin >