plastron (Noun) — The ornamental front of a woman's bodice or shirt.
plastron (Noun) — The front of man's dress shirt.
plastron (Noun) — A metal breastplate that was worn under a coat of mail.
plastron (Noun) — A large pad worn by a fencer to protect the chest.
plastron (Noun) — (zoology) the part of a turtle's shell forming its underside.