tombstone

A gravestone.

A stone placed over a grave, to preserve the memory of the deceased; a sepulchral monument.

In heraldry, a bearing representing a sarcophagus or altar-tomb, usually having a large Latin cross on the slab or top.

A stone erected over a grave, to preserve the memory of the deceased.

A headstone marking the person’s grave.

The symbol “∎” marking the end of a proof.

For a surfboard to stand upright half-submerged in the water (like a tombstone, above) because the surfer is underwater with his or her legrope pulled tight. Often this indicates a surfer in difficulty, either held down by the power of a wave or unconscious and unable to get to the surface.

a stone that is used to mark a grave