twirl vs flexure

twirl and flexure both are nouns.

Word	Noun	Adjective	Verb	Adverb
twirl	Yes	No	Yes	No
flexure	Yes	No	No	No

As nouns, flexure is a hypernym of twirl; that is, flexure is a word with a broader meaning than twirl:

twirl: a sharp bend in a line produced when a line having a loop is pulled tight
flexure: an angular or rounded shape made by folding

Other hypernyms of twirl include bend, crease, crimp, fold, plication.

twirl (noun)	flexure (noun)
the act of rotating rapidly	act of bending a joint; especially a joint between the bones of a limb so that the angle between them is decreased
a sharp bend in a line produced when a line having a loop is pulled tight	an angular or rounded shape made by folding
	the state of being flexed (as of a joint)

twirl (verb)	flexure (verb)
turn in a twisting or spinning motion
cause to spin