es·​tu·​ary ˈes-chə-ˌwer-ē How to pronounce estuary (audio)
plural estuaries
: a water passage where the tide meets a river current
especially : an arm of the sea at the lower end of a river

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A partly enclosed coastal body of water in which river water is mixed with seawater is called an estuary. An estuary is thus defined by salinity rather than geography. Many coastal features designated by other names are in fact estuaries (for instance, Chesapeake Bay). Some of the oldest continuous civilizations have flourished in estuarine environments (for example, the Tigris and Euphrates rivers, the Nile delta, and the Ganges delta). Cities such as London (Thames River), New York (Hudson River), and Montreal (St. Lawrence River) developed on estuaries and became important commercial centers.

Examples of estuary in a Sentence

the city sits on the shores of a deep estuary where the Hudson River meets the Atlantic Ocean
Recent Examples on the Web There are marine and estuary topographies, cypresses and mangroves. Evie Carrick, Travel + Leisure, 4 Feb. 2024 Pollution from these farms, most of which are in tropical climates, is substantial, dumping organic waste, chemicals, and antibiotics into groundwater and estuaries, and salt into agricultural land. Patrik Jonsson, The Christian Science Monitor, 30 Jan. 2024 When water supply gets tight, the bays and estuaries typically are first to see their allocations revoked while cities keep dam gates closed. Dylan Baddour, WIRED, 27 Jan. 2024 The reserve is also an important spot along the Pacific Flyway, a major bird migration route, where seabirds nest in eucalyptus groves and fatten up in the rich estuary habitat. Alix Soliman, Hartford Courant, 3 Jan. 2024 In his own research, Whitehead has shown that Atlantic killifish, a small silvery fish found off eastern Canada and the United States, has adapted to live comfortably in estuaries plagued by heavy industrial pollution. Brian Owens, Smithsonian Magazine, 26 Jan. 2024 De Lappe, for one, has spent years chronicling abandoned and sunken boats in the estuary. Will McCarthy, The Mercury News, 16 Jan. 2024 Any further spills would permanently damage the Big Cypress ecosystem and flow to the coastal estuaries and beaches of South Florida, all while poisoning the aquifer that supplies all of South Florida with drinking water. Talbert Cypress, Sun Sentinel, 11 Jan. 2024 Florida is no stranger to ferocious storms, but the state's Apalachee Bay — an estuary 25 miles south of Tallahassee — usually dodges the most fearsome weather conditions. Daniel Arkin, NBC News, 30 Aug. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'estuary.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Latin aestuarium, from aestus boiling, tide; akin to Latin aestas summer — more at edify

First Known Use

1538, in the meaning defined above

Time Traveler
The first known use of estuary was in 1538

Dictionary Entries Near estuary

Cite this Entry

“Estuary.” Dictionary, Merriam-Webster, Accessed 25 Feb. 2024.

Kids Definition


es·​tu·​ary ˈes-chə-ˌwer-ē How to pronounce estuary (audio)
plural estuaries
: a passage where the tide meets a river current
especially : an arm of the sea at the lower end of a river

More from Merriam-Webster on estuary

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