noun an iron breastplate, worn under the hauberk.
2. plastron ·noun a piece of leather stuffed or padded, worn by fencers to protect the breast.
3. plastron ·noun the ventral shield or shell of tortoises and turtles. ·see testudinata.
4. plastron ·noun a trimming for the front of a woman's dress, made of a different material, and narrowing from the shoulders to the waist.