lament vs poem

lament and poem both are nouns.

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

As nouns, poem is a hypernym of lament; that is, poem is a word with a broader meaning than lament:

Other hypernyms of lament include verse form.

lament (noun)	poem (noun)
a mournful poem; a lament for the dead	a composition written in metrical feet forming rhythmical lines
a song or hymn of mourning composed or performed as a memorial to a dead person
a cry of sorrow and grief

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