warm up vs warm-up

warm up and warm-up both are nouns.

Word	Noun	Adjective	Verb	Adverb
warm up	Yes	No	Yes	No
warm-up	Yes	No	No	No

warm up (noun)	warm-up (noun)
performing mild exercises to prepare for some more strenuous activity	exercising in preparation for strenuous activity

warm up (verb)	warm-up (verb)
make one's body limber or suppler by stretching, as if to prepare for strenuous physical activity
cause to do preliminary exercises so as to stretch the muscles
get warm or warmer
become more friendly or open
run until the normal working temperature is reached