A headstone marking a person's grave.
The symbol "∎" marking the end of a proof.
A marker that takes the place of deleted data, allowing for replication of the deletion across servers etc.
A crashdump.
An unusual morphological feature on an electrocardiogram indicative of acute myocardial infarction, characterized by a massive ST elevation.
To take part in tombstoning: to jump into the sea, etc. from a cliff or other high point so as to enter the water vertically straight.
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.
To replace (an object or data) with a tombstone marker.