firm vs tighten

firm is a noun but tighten is not a noun.

Word	Noun	Adjective	Verb	Adverb
firm	Yes	Yes	Yes	Yes
tighten	No	No	Yes	No

As verbs, tighten is a hypernym of firm; that is, tighten is a word with a broader meaning than firm:

As verbs, tighten is a hypernym of firm; that is, tighten is a word with a broader meaning than firm:

Other hypernyms of firm include fasten.

firm (noun)	tighten (noun)
the members of a business organization that owns or operates one or more establishments

firm (adjective)	tighten (adjective)
unwavering in devotion to friend or vow or cause
securely fixed in place
strong and sure
not soft or yielding to pressure
possessing the tone and resiliency of healthy tissue
marked by firm determination or resolution; not shakable
securely established
not subject to revision or change
(of especially a person's physical features) not shaking or trembling
not liable to fluctuate or especially to fall

firm (verb)	tighten (verb)
become taut or tauter	become tight or tighter
make taut or tauter	make tight or tighter
	severely restrict in scope or extent
	narrow or limit

firm (adverb)	tighten (adverb)
with resolute determination