freshen vs vent

freshen is not a noun while vent is a noun.

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

As verbs, vent is a hyponym of freshen; that is, vent is a word with a more specific, narrower meaning than freshen:

Other hyponyms of freshen include air, air out, ventilate.

freshen (noun)	vent (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

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