Ossify
To make into bone; to convert cartilage or fibrous tissue into bone.</P> The skeleton initially consists mainly of cartilage which is gradually transformed into bone during development.
This bone-building process is termed 'ossification.' Bone is 'osseous' tissue.
'Os' is a synonym for 'bone.'</P> The word 'os' is Latin and is related to the Greek 'osteon' which also means 'bone.'