[buhn-yuh
n] 
| inflammation of the synovial bursa of the great toe, usually resulting in enlargement of the joint and lateral displacement of the toe. |
| bun·ion (bŭn'yən) n. A painful, inflamed swelling of the bursa at the first joint of the big toe, characterized by enlargement of the joint and lateral displacement of the toe. [Probably alteration of obsolete bunny, swelling, from Middle English bony, perhaps from Old French bugne; see bun1.] |
bunion bun·ion (bŭn'yən)
n.
A localized swelling at either the medial or dorsal aspect of the first joint of the big toe, caused by an inflamed bursa.
bunion
type of bursitis that appears as a bulge covered by thickened skin occurring at the base of the big toe, where friction against the side of the shoe takes place. The protuberance is due to a swelling of the bursa mucosa, a closed sac filled with a clear, lubricating fluid. The bunion causes pain, localized tenderness, and limitation of motion, and it results in permanent deformation, forcing the toe toward the little toe.
Learn more about bunion with a free trial on Britannica.com.