lament vs bemoan

lament is a noun but bemoan is not a noun.

Word	Noun	Adjective	Verb	Adverb
lament	Yes	No	Yes	No
bemoan	No	No	Yes	No

As verbs, lament and bemoan are synonyms defined as:

Other synonyms of lament include bewail, deplore.

lament (noun)	bemoan (noun)
a mournful poem; a lament for the dead
a song or hymn of mourning composed or performed as a memorial to a dead person
a cry of sorrow and grief

lament (verb)	bemoan (verb)
regret strongly	regret strongly
express grief verbally