PLASTRON

noun see: piastre Date: circa 1507 1. a metal breastplate formerly worn under the hauberk, a quilted pad worn in fencing practice to protect the chest, waist, and the side on which the weapon is held, the ventral part of the shell of a tortoise or turtle consisting typically of nine symmetrically placed bones overlaid by horny plates, 3. a trimming like a bib for a woman's dress, dickey 1a, a thin film of air held by water-repellent hairs of some aquatic insects