- 1any of a number of bivalve mollusks with rough irregular shells. Several kinds are eaten (especially raw) as a delicacy and may be farmed for food or pearls.
- a true oyster (family Ostreidae), in particular the edible American oyster (Crassostrea virginica). a similar bivalve of another family, in particular the thorny oysters (Spondylidae), wing oysters (Pteriidae), and saddle oysters (Anomiidae).
verb[no object] (usually as noun oystering)
Middle English: from Old French oistre, via Latin from Greek ostreon; related to osteon 'bone' and ostrakon 'shell or tile'