melaena vs melena

melaena and melena both are nouns.

Word	Noun	Adjective	Verb	Adverb
melaena	Yes	No	No	No
melena	Yes	No	No	No

As nouns, melaena and melena are synonyms defined as:

melaena and melena: abnormally dark tarry feces containing blood (usually from gastrointestinal bleeding)

melaena (noun)	melena (noun)
abnormally dark tarry feces containing blood (usually from gastrointestinal bleeding)	abnormally dark tarry feces containing blood (usually from gastrointestinal bleeding)