estuary

American  

[es-choo-er-ee] / ˈɛs tʃuˌɛr i /

noun

plural

estuaries

1. that part of the mouth or lower course of a river in which the river's current meets the sea's tide.

2. an arm or inlet of the sea at the lower end of a river.

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estuary British  

/ ˌɛstjʊˈɛərɪəl, ˈɛstjʊərɪ /

noun

1. the widening channel of a river where it nears the sea, with a mixing of fresh water and salt (tidal) water

2. an inlet of the sea

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estuary Scientific  

/ ĕs′cho̅o̅-ĕr′ē /

1. The wide lower course of a river where it flows into the sea. Estuaries experience tidal flows and their water is a changing mixture of fresh and salt.

2. An arm of the sea that extends inland to meet the mouth of a river.

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estuary Cultural  

1. A wide body of water formed where a large river meets the sea. It contains both fresh and salt water.

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Other Word Forms

• estuarial
  adjective

Etymology

Origin of estuary

First recorded in 1530–40; from Latin aestuārium “channel, creek, inlet,” from aestu(s) “fire, heat, tide” + -ārium -ary

Explanation

An estuary is the place in the water where a tide and a river current meet, like the estuary at New York Harbor, where the Hudson River meets the Atlantic Ocean. Estuary, pronounced "ES-choo-air-ee," comes from the Latin word aestuarium, meaning "a tidal marsh or opening." The calm waters of an estuary, where the mouth of a river connects with the open sea and fresh water mixes with salty ocean water, makes the perfect home for many species of aquatic plants and animals. Chesapeake Bay and Puget Sound are estuaries.

Example Sentences

The reserve is situated on the south bank of the River Ouse where the waterway widens into the Humber Estuary.

From BBC • Mar. 7, 2026

Chris Peregrin, who manages the Tijuana Estuary for the state park system, said the nonprofit Tijuana Estuary Foundation has been a good partner, and the president of the foundation board is guess who:

From Los Angeles Times • Feb. 14, 2026

There had been talk for years about turning the underappreciated Tijuana River Estuary, part of which was used as a dumping ground, into something useful.

From Los Angeles Times • Feb. 14, 2026

A sandy seaside resort at the mouth of the Mersey Estuary, the beach offers striking views over the Liverpool city skyline.

From BBC • Feb. 13, 2026

Race day, April 13, was again rainy, and a stiff headwind blew out of the south, up the length of the Oakland Estuary.

From "The Boys in the Boat: Nine Americans and Their Epic Quest for Gold at the 1936 Berlin Olympics" by Daniel James Brown

Related Words

• inlet
• waterway