n. A breastplate; a garment or part of a garment covering the breast. , , , n. In herpetology: The ventral part of the shell of a chelonian or testudinate; the lower shell, or under side of the shell, of a turtle or tortoise: more or less opposed to carapace.n. One of the similar exoskeletal plates developed upon the under side of the body of certain Amphibia, as the Labyrinthodonta.n. In mammalogy, the ventral shield or cuirass of the glyptodons or fossil armadillos.n. In anatomy, the sternum with the costal cartilages attached, as removed in autopsies.n. In ornithology, a colored area on the breast or belly of a bird, like or likened to a shield.n. In the Echinodermata, a space surrounded by the subanal fasciole lying beneath the anus, in spatangoid echinoids.