Osseous means bony. If your next door neighbor buried their old pet cat in their yard, watch that your dog doesn’t go digging over there, looking for an osseous treat.
Osseous comes from the Latin word for bone, oss. You can use osseous to describe things that are literally made of bone, like the osseous structure of your skeleton. You can also use osseous to describe things that have hardened like bones. You might find an osseous piece of taffy in your coat pocket, left there last summer. In that case you could say the taffy ossified.