mourner vs lamenter

mourner and lamenter both are nouns.

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

As nouns, mourner and lamenter are synonyms defined as:

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

Other synonyms of mourner include griever, sorrower.

mourner (noun)	lamenter (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)