n. [ OE. bocler, OF. bocler, F. bouclier, a shield with a boss, from OF. bocle, boucle, boss. See Buckle, n. ] 1. 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. [ 1913 Webster ]

☞ In the sword and buckler play of the Middle Ages in England, the buckler was a small shield, used, not to cover the body, but to stop or parry blows. [ 1913 Webster ]

2. (Zool.) (a) One of the large, bony, external plates found on many ganoid fishes. (b) The anterior segment of the shell of trilobites. [ 1913 Webster ]

3. (Naut.) 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. [ 1913 Webster ]

Blind buckler (Naut.), a solid buckler. --
Buckler mustard (Bot.), a genus of plants (Biscutella) with small bright yellow flowers. The seed vessel on bursting resembles two bucklers or shields. --
Buckler thorn, a plant with seed vessels shaped like a buckler. See Christ's thorn. --
Riding buckler (Naut.), a buckler with a hole for the passage of a cable. [ 1913 Webster ]

v. t. To shield; to defend. [ Obs. ] [ 1913 Webster ]

Can Oxford, that did ever fence the right,
Now buckler falsehood with a pedigree? Shak. [ 1913 Webster ]

a. Having a head like a buckler. [ 1913 Webster ]