megrim

[Middle English 'migrem', variant of 'migraine', from Old French 'migraigne', from vulgar pronunciation of Late Latin 'hēmicrānia', from Greek 'hēmikrāniā', from 'hēmi-', half + 'krānion', head]
n.
1. A severe recurring vascular headache, usually confined to one side of the head.
2. A caprice or fancy -often used in the plural.
3. Depression or unhappiness -often used in the plural.
4. Any of numerous diseases of animals marked by disturbance of equilibrium and abnormal gait and behavior —usually used in plural.
5. A European flounder, more commonly known as a scaldfish.