OYSTER

noun Usage: often attributive see: osseous Date: 13th century 1. any of various marine bivalve mollusks (family Ostreidae) that have a rough irregular shell closed by a single adductor muscle and include commercially important shellfish, any of various mollusks resembling or related to the ~s, something that is or can be readily made to serve one's personal ends , a small mass of muscle contained in a concavity of the pelvic bone on each side of the back of a fowl, an extremely taciturn person, a grayish-white color