crawl vs flex

crawl and flex both are nouns.

Word	Noun	Adjective	Verb	Adverb
crawl	Yes	No	Yes	No
flex	Yes	No	Yes	No

As verbs, flex is a hypernym of crawl; that is, flex is a word with a broader meaning than crawl:

Other hypernyms of crawl include bend.

crawl (noun)	flex (noun)
a slow mode of locomotion on hands and knees or dragging the body	the act of flexing
a swimming stroke; arms are moved alternately overhead accompanied by a flutter kick
a very slow movement

crawl (verb)	flex (verb)
move slowly; in the case of people or animals with the body near the ground	cause (an object) to assume a crooked or angular form
swim by doing the crawl	bend a joint
show submission or fear	form a curve
be full of	contract
feel as if crawling with insects	exhibit the strength of