A severe recurring headache, usually affecting only one side of the head, characterized by sharp pain and often accompanied by nausea, vomiting, and visual disturbances.
[Middle English, from Old French, from Late Latin hēmicrānia, from Greek hēmikrāniā : hēmi-, hemi- + krānion, head; see ker-1 in the Appendix of Indo-European roots.]
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