What's the noun for tombless? Here's the word you're looking for.
tomb
A small building (or "vault") for the remains of the dead, with walls, a roof, and (if it is to be used for more than one corpse) a door. It may be partly or wholly in the ground (except for its entrance) in a cemetery, or it may be inside a church proper or in its crypt. Single tombs may be permanently sealed; those for families (or other groups) have doors for access whenever needed.
A pit in which the dead body of a human being is deposited; a grave.
“He is buried in an elaborate tomb in New York, a place he never liked.”
“Some gilded bronze shoes and horse trappings were found at the entrance of the tomb.”
“He spent two nights in succession at his Grandfather's tomb. The second night he received a vision in which his Grandfather appeared to him, promising him a place in Paradise.”
