vent vs freshen

vent is a noun but freshen is not a noun.

Word	Noun	Adjective	Verb	Adverb
vent	Yes	No	Yes	No
freshen	No	No	Yes	No

As verbs, freshen is a hypernym of vent; that is, freshen is a word with a broader meaning than vent:

Other hypernyms of vent include refresh.

vent (noun)	freshen (noun)
activity that frees or expresses creative energy or emotion
external opening of urinary or genital system of a lower vertebrate
a hole for the escape of gas or air
a slit in a garment (as in the back seam of a jacket)
a fissure in the earth's crust (or in the surface of some other planet) through which molten lava and gases erupt

vent (verb)	freshen (verb)
expose to cool or cold air so as to cool or freshen	make fresh again
give expression or utterance to	become or make oneself fresh again
	make (to feel) fresh