buckler

• ⇰ A kind of shield, of various shapes and sizes, worn on one of the arms (usually the left) for protecting the front of the body.
• ⇰ One of the large, bony, external plates found on many ganoid fishes.
• ⇰ A block of wood or plate of iron made to fit a hawse hole, or the circular opening in a half-port, to prevent water from entering when the vessel pitches.

• ⇰ To shield; to defend.