tighten vs bound

tighten is not a noun while bound is a noun.

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

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

Other hypernyms of tighten include confine, limit, restrict, throttle, trammel.

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

Other hypernyms of tighten include confine, limit, restrict, throttle, trammel.

tighten (noun)	bound (noun)
	a light, self-propelled movement upwards or forwards
	the greatest possible degree of something
	the line or plane indicating the limit or extent of something
	a line determining the limits of an area

tighten (adjective)	bound (adjective)
	confined by bonds
	secured with a cover or binding; often used as a combining form
	held with another element, substance or material in chemical or physical union
	confined in the bowels
	headed or intending to head in a certain direction; often used as a combining form as in `college-bound students'
	bound by an oath
	covered or wrapped with a bandage
	bound by contract
	(usually followed by `to') governed by fate

tighten (verb)	bound (verb)
become tight or tighter	place limits on (extent or amount or access)
make tight or tighter	spring back; spring away from an impact
severely restrict in scope or extent	move forward by leaps and bounds
narrow or limit	form the boundary of; be contiguous to