Noah Webster
Ossify
OS'SIFY, verb transitive [Latin os, bone, anf facio, to form.]
To form bone; to change from a soft animal substance into bone, or convert into a substance of the hardness of bones. This is done by the deposition of calcarious phosphate or carbonate on the part.
OS'SIFY, verb intransitive To become bone; to change from soft matter into a substance of bony hardness.