plural estuaries
Synonyms of estuary
: 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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
In May and June, more than 250 species of Arctic birds nest or pass over the Churchill River estuary. Evie Carrick, Travel + Leisure, 26 July 2026 Isla Jesucita provides secluded coves, tropical forest and expansive views across the estuary. Rafa Sales Ross, Variety, 24 July 2026 Onlookers watched the storm surge at the Lake Pontchartrain estuary, with kids splashing in the floodwaters as Bertha approached the Louisiana Coast. ABC News, 23 July 2026 Nicknamed the Emerald Coast, this land has miles of golden-sand beach on one side, mangrove estuaries, evergreen rainforest, and Sierra Madre mountains on the other. Laura Dannen Redman, Robb Report, 23 July 2026 See All Example Sentences for estuary

Word History

Etymology

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

First Known Use

circa 1552, in the meaning defined above

Time Traveler
The first known use of estuary was circa 1552

Browse Nearby Words

Cite this Entry

“Estuary.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/estuary. Accessed 2 Aug. 2026.

Kids Definition

plural estuaries
: a passage where the tide meets a river current
especially : an arm of the sea at the lower end of a river
estuarine
ˈes-chə-wə-ˌrīn
adjective

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