Borrowed from Middle French migraigne, semi-learned borrowing from Late Latin hēmicrānia (“pain in one half of the head”), from Ancient Greek ἡμικρᾱνίᾰ (hēmikrāníă), from ἡμι- (hēmi-, “hemi-, half”) + κρανίον (kraníon, “skull”) (whence also English cranium). Doublet of migraine and hemicrania.