Webster's Revised Unabridged Dictionary · 1913

migraine

migraine , noun

[French migraine, Late Latin hemigrania, Latin hemicrania, hemicranium, Greek "hmikrani`a; "hmi- half + krani`on skull. See Hemi- and Cranium, and compare Hemicrania, Migraine.]

1.
A kind of intense sick or nervous headache, usually periodical and confined to one side of the head; called also migraine headache. Same as megrim.