buckler

Etymology

From Middle English bukler, bokler, bokeler, bokeleer, from Old French bocler, boucler, bucler, (French bouclier) from Vulgar Latin *bucculārius (“bossed”), from Latin buccula (“boss”). Merged with buckle + -er.

noun

1. One who buckles something.
   Bucklers will be assigned to buckle up drivers in the morning and make sure they stay buckled up. 1986, Press Summary - Illinois Information Service, page 6724
2. A kind of shield, of various shapes and sizes, held in the hand or worn on the arm (usually the left), for protecting the front of the body. 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.
3. (obsolete) A shield resembling the Roman scutum. In modern usage, a smaller variety of shield is usually implied by this term.
   The target or buckler was carried by the heavy armed foot, it answered to the scutum of the Romans; its form was sometimes that of a rectangular parallelogram, but more commonly had it's bottom rounded off; it was generally convex, being curved in it's breadth. 1786, Francis Grose, A Treatise on Ancient Armour and Weapons, page 22
4. (zoology) One of the large, bony, external plates found on many ganoid fishes.
   Most zeids have spiny projections or bucklers at the dorsal- and anal-fin bases and bony plates on the ventral surface of the abdomen. 2000, Jeffrey Martin Leis, Brooke M. Carson-Ewart, The Larvae of Indo-Pacific Coastal Fishes, page 186
5. (zoology) The anterior segment of the shell of a trilobite.
6. (nautical) 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.

verb

1. (transitive, obsolete) To shield; to defend.