A Reverse Vault is a vault in which the dog flips off the handler’s body.
The Reverse Vault, aka Rebound, can be done off of any part of the body, and the part of the body that the vault happens from usually is reflected in the name: Reverse Leg Vault, Reverse Chest Vault, Reverse Back Vault.
Leg Rebound, Chest Rebound, Back Rebound, etc. is another popular phrasing.
Rebounds or Reverse Vaults tend to land on the same side of the handler from which the dog leapt.