Tombstone and Tomb stone

Tombstone noun - A shaped stone laid over or erected near a grave and usually bearing an inscription to identify and preserve the memory of the deceased.

Tomb stone and tombstone are semantically related. In some cases you can replace phrase "Tomb stone" with "Tombstone", this terms are similar.

Tombstone and tomb stone are semantically related. You can use "Tombstone" instead a noun phrase "Tomb stone".