1) Neural condition characterised by a severe recurrent vascular headache, usually on one side of the head, often accompanied by nausea, vomiting, and photophobia, sometimes preceded by sensory disturbances; triggers include allergic reactions, excess carbohydrates or iodine in the diet, alcohol, bright lights or loud noises.

2) A class of disabling primary headache disorders, characterised by recurrent unilateral pulsatile headaches. The two major subtypes are common migraine (without aura) and classic migraine (with aura or neurological symptoms).