oyster
nounUK /ˈɔɪ.stər/
US /ˈɔɪ.stɚ/
A small sea animal with a hard shell that lives in the ocean.
We found an oyster on the beach and looked at its rough shell.
OTHER MEANINGS
2. A dark, salty liquid made from oysters that people eat as food.
He added a splash of oyster sauce to the stir-fry.
3. A person who keeps secrets and says very little.
She stayed quiet all night, as tight-lipped as an oyster.
4. Something from which a valuable thing can be obtained.
The old library was an oyster of hidden knowledge.