megrim vs migraine

megrim and migraine both are nouns.

Word	Noun	Adjective	Verb	Adverb
megrim	Yes	No	No	No
migraine	Yes	No	No	No

As nouns, megrim and migraine are synonyms defined as:

megrim and migraine: a severe recurring vascular headache; occurs more frequently in women than men

Other synonyms of megrim include hemicrania, sick headache.

megrim (noun)	migraine (noun)
a severe recurring vascular headache; occurs more frequently in women than men	a severe recurring vascular headache; occurs more frequently in women than men