Meaning of “warm (sb/sth) up” - Learner’s Dictionary

warm (sb/sth) up

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

to become warmer or to make someone or something warmer:

The house soon warms up with the heating on.

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