Ex·os-tō'sis, n.

n. [Gr. ἐξόστωσις, from ἐξ, out, and ὀστέον, bone; Fr. exostose.]

1. (Anat.) 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.