Ex`os*to"sis (?), n. [NL., fr. Gr. ; out + bone: cf. F exostose.]
1. Med.
Any protuberance of a bone which is not natural; an excrescence or morbid enlargement of a bone.
Coxe.
2. Bot.
A knot formed upon or in the wood of trees by disease.
© Webster 1913.