Meaning of “warm up” - Learner’s Dictionary

warm up

phrasal verb with warm uk us /wɔːm/ verb [ I, T ]

to do gentle exercises in order to prepare yourself for more energetic exercise:

They were warming up before the match.
warm-up uk us /ˈwɔːmʌp/ noun [ C ]

(Definition of “warm up” from the Cambridge Learner’s Dictionary © Cambridge University Press)