1. (n.) 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.

2. (n.) One of the large, bony, external plates found on many ganoid fishes.

3. (n.) The anterior segment of the shell of trilobites.

4. (n.) 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.

5. (v. t.) To shield; to defend.

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