Tombstones

noun

1. A headstone marking a person's grave.
2. The symbol "∎" marking the end of a proof.
3. A marker that takes the place of deleted data, allowing for replication of the deletion across servers etc.
4. A crashdump.
5. An unusual morphological feature on an electrocardiogram indicative of acute myocardial infarction, characterized by a massive ST elevation.