forever vs evermore

forever and evermore both are adverbs.

Word	Noun	Adjective	Verb	Adverb
forever	No	No	No	Yes
evermore	No	No	No	Yes

As adverbs, forever and evermore are synonyms defined as:

Other synonyms of forever include eternally, everlastingly.

forever (adverb)	evermore (adverb)
for a limitless time	for a limitless time
for a very long or seemingly endless time	at any future time; in the future
invariably