a large flat shellfish. Some types of oyster can be eaten and others produce shiny white jewels called pearls. 牡蛎；蚝 
Oxford Collocations DictionaryOyster is used before these nouns:- mushroom
- sauce
- shell
- …
Word OriginMiddle English: from Old French oistre, via Latin from Greek ostreon; related to osteon ‘bone’ and ostrakon ‘shell or tile’.
Idioms
the world is your oyster
there is no limit to the opportunities open to you 世界是属于你的；你的前途无量 With talent like that, the world is her oyster. 有了那样的天赋，世界就是她的了。