oyster

Etymology

From Middle English oystre, from Old English ostre, reinforced or superseded by Anglo-Norman oistre, which is from Old French oistre, uistre (compare modern French huître); both lines (Old English and Old French) from Latin ostrea, from Ancient Greek ὄστρεον (óstreon).

noun

1. Any of certain marine bivalve mollusks, especially those of the family Ostreidae (the true oysters), usually found adhering to rocks or other fixed objects in shallow water along the seacoasts, or in brackish water in the mouth of rivers.
   Why, then the world's mine oyster 1597-8, William Shakespeare, The Merry Wives of Windsor, act II, scene II
   He was a bold man that first ate an oyster. 1731, Jonathan Swift, “Polite Conversation”, in The Works of Jonathan Swift, volume 2, published 1841, page 344
2. The delicate morsel of dark meat contained in a small cavity of the bone on each side of the lower part of the back of a fowl.
3. A pale beige color tinted with grey or pink, like that of an oyster.
   oyster:
4. (colloquial, by analogy) A person who keeps secrets.
5. (UK, slang) A shoplifter.
6. (UK, slang) A public transport travelcard.

adj

1. Of a pale beige colour tinted with grey or pink, like that of an oyster.

verb

1. (intransitive) To fish for oysters.