loosen up vs behave

loosen up and behave both are verbs.

Word	Noun	Adjective	Verb	Adverb
loosen up	No	No	Yes	No
behave	No	No	Yes	No

As verbs, behave is a hypernym of loosen up; that is, behave is a word with a broader meaning than loosen up:

loosen up: become less tense, less formal, or less restrained, and assume a friendlier manner
behave: behave in a certain manner; show a certain behavior; conduct or comport oneself

Other hypernyms of loosen up include acquit, act, bear, carry, comport, conduct, deport, do.

loosen up (verb)	behave (verb)
become less tense, rest, or take one's ease	behave in a certain manner; show a certain behavior; conduct or comport oneself
cause to feel relaxed	behave well or properly
make one's body limber or suppler by stretching, as if to prepare for strenuous physical activity
cause to become unblocked
become less tense, less formal, or less restrained, and assume a friendlier manner