Pronunciation: (big'hed', -hed"), [key]
1. Informal.an excessive estimate of one's importance; conceit.
2. Vet. Pathol.
a. an inflammatory swelling of the tissues of the head of sheep, caused by the anaerobic bacillus Clostridium novyi.
b. enlargement of the head and jawbones of horses resulting from nutritional hyperthyroidism.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.