venthole vs vent-hole

venthole and vent-hole both are nouns.

Word	Noun	Adjective	Verb	Adverb
venthole	Yes	No	No	No
vent-hole	Yes	No	No	No

As nouns, venthole and vent-hole are synonyms defined as:

Other synonyms of venthole include blowhole, vent.

venthole (noun)	vent-hole (noun)
a hole for the escape of gas or air	a hole for the escape of gas or air