lamenter vs mourner

lamenter and mourner both are nouns.

Word	Noun	Adjective	Verb	Adverb
lamenter	Yes	No	No	No
mourner	Yes	No	No	No

As nouns, lamenter and mourner are synonyms defined as:

lamenter and mourner: a person who is feeling grief (as grieving over someone who has died)

Other synonyms of lamenter include griever, sorrower.

lamenter (noun)	mourner (noun)
a person who is feeling grief (as grieving over someone who has died)	a person who is feeling grief (as grieving over someone who has died)