1 a a fencer's leather-covered breastplate. b a lancer's breast-covering of facings-cloth.
2 a an ornamental front on a woman's bodice. b a man's starched shirt-front.
3 a the ventral part of the shell of a tortoise or turtle. b the corresponding part in other animals.
4 hist. a steel breastplate.
F f. It. piastrone augment. of piastra breastplate, f. L emplastrum PLASTER