oyster

American  

[oi-ster] / ˈɔɪ stər /

noun

1. any of several edible, marine, bivalve mollusks of the family Ostreidae, having an irregularly shaped shell, occurring on the bottom or adhering to rocks or other objects in shallow water.

2. the oyster-shaped bit of dark meat in the front hollow of the side bone of a fowl.

3. Slang. a closemouthed or uncommunicative person, especially one who keeps secrets well.

4. something from which a person may extract or derive advantage.

   The world is my oyster.

5. oyster white.

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verb (used without object)

1. to dredge for or otherwise take oysters.

oyster British  

/ ˈɔɪstə /

noun

1. 1. any edible marine bivalve mollusc of the genus Ostrea, having a rough irregularly shaped shell and occurring on the sea bed, mostly in coastal waters

   2. ( as modifier )

      oyster farm

      oyster knife

2. any of various similar and related molluscs, such as the pearl oyster and the saddle oyster ( Anomia ephippium )

3. the oyster-shaped piece of dark meat in the hollow of the pelvic bone of a fowl

4. something from which advantage, delight, profit, etc, may be derived

   the world is his oyster

5. informal a very uncommunicative person

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verb

1. (intr) to dredge for, gather, or raise oysters

oyster Idioms  

1. see world is one's oyster.

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Etymology

Origin of oyster

1325–75; Middle English oistre < Middle French < Latin ostrea < Greek óstreon; see ostracize

Explanation

An oyster is an animal that lives in the sea, a rough-shelled mollusk. To find a pearl inside an oyster, you first have to find a "pearl oyster" — a rare cousin of the oysters people commonly eat. You can usually tell you've found an oyster on the beach because its shell is bumpy and irregular, unlike the smoother clams or mussels you might see. There are few kinds of oysters that are edible (both cooked and raw), and many others that aren't. You may have heard the expression "the word ls your oyster," which is one of Shakespeare's many linguistic inventions; he means the world is yours to seize, open, and use as you wish.

Example Sentences

“The Oyster Diaries” is very much in the Percy philosophical mode, not entirely to its advantage.

From The Wall Street Journal • Apr. 23, 2026

In “The Oyster Diaries,” Delery runs into Claude, a “portly fifty-year-old” living in seclusion in an overgrown plantation.

From The Wall Street Journal • Apr. 23, 2026

Oyster reefs do more than support oyster populations.

From Science Daily • Apr. 6, 2026

You could see Hog Island Oyster Company across the bay, but there were no sounds.

From Los Angeles Times • Oct. 7, 2025

The 707 slammed into the estate owned by the father of the tennis champion John McEnroe, in the posh Long Island town of Oyster Bay.

From "Outliers" by Malcolm Gladwell

Related Words

• clam
• conch
• crawfish
• crustacean
• lobster
• mollusk
• mussel
• prawn
• scallop
• shrimp
• snail