Megrim: Migraine. Usually periodic attacks of headaches on one or both sides of the head. Megrim (migraine) may be accompanied by nausea, vomiting, increased sensitivity of the eyes to light (photophobia), increased sensitivity to sound (phonophobia), dizziness, blurred vision, cognitive disturbances, and other symptoms. Some megrims (migraines) do not include headache. They may or may not be preceded by an aura.
"Megrim" and "migraine" share a meaning and an etymological origin. Latin and Greek speakers called their pain, if it was just on one side of the head, "hemicrania" or "hemikrania," from the Greek terms "hemi-" meaning "half" plus "kranion" meaning "cranium" = half-skull. The French used "migraine," a modification of "hemicrania," for the same condition. English twice borrowed "migraine" from the French. In the 14th century, the French term was modified to form "migreime," which gave rise to "megrim." Later, in the 15th century, the French "migraine" was borrowed again and its spelling stayed intact. "Megrim" and "migraine" now can be used interchangeably.
The term "megrim" also refers to vertigo or dizziness and, in the non-medical arena, to a fancy or whim or to low spirits.