peradventure vs possibly

peradventure is a noun but possibly is not a noun.

Word	Noun	Adjective	Verb	Adverb
peradventure	Yes	No	No	Yes
possibly	No	No	No	Yes

As adverbs, peradventure and possibly are synonyms defined as:

Other synonyms of peradventure include maybe, mayhap, perchance, perhaps.

peradventure (noun)	possibly (noun)
doubt or uncertainty as to whether something is the case

peradventure (adverb)	possibly (adverb)
by chance	by chance
	to a degree possible of achievement or by possible means