From WordNet (r) 3.0 (2006) :
callus
n 1: an area of skin that is thick or hard from continual
pressure or friction (as the sole of the foot) [syn:
callosity, callus]
2: bony tissue formed during the healing of a fractured bone
3: (botany) an isolated thickening of tissue, especially a stiff
protuberance on the lip of an orchid
v 1: cause a callus to form on; "The long march had callused his
feet"
2: form a callus or calluses; "His foot callused"