Definition of "megrim"

(now rare) A headache; a migraine.

(now rare) A fancy, a whim, a caprice.

(in the plural) See megrims (“depression; any of various diseases of animals”).  examples

A type of flatfish of the genus Lepidorhombus native to the northeastern Atlantic Ocean; specifically, the Cornish sole, sail-fluke, or whiff (Lepidorhombus whiffiagonis).  examples