Buckler

1. v. t. To shield; to defend.
2. 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.
3. n. One of the large, bony, external plates found on many ganoid fishes.
4. n. The anterior segment of the shell of trilobites.
5. 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.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.