estuary

American  

[es-choo-er-ee] / ˈɛs tʃuˌɛr i /

noun

estuaries plural

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

Derived Forms

• estuarial
  adjective

Inflected Forms

noun

• estuaries
  plural

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

Much of the uncaptured Mexican waste flows into the Tijuana River, which crosses a U.S. estuary before reaching the Pacific.

From The Wall Street Journal • May 4, 2026

Algae-smothered seagrass meadows in the Thames estuary along the Essex coast and the Firth of Forth on the east coast of Scotland were among those worst affected.

From BBC • May 2, 2026

The environment 132 million years ago would have looked very different from today's coastline, estuary, and developed landscape.

From Science Daily • Apr. 24, 2026

The tidal Scheldt river estuary is the main maritime access route to Antwerp port, along with several narrower canals primarily used for inland navigation.

From Barron's • Apr. 10, 2026

But Coyotito—he was the one—he wore a blue sailor suit from the United States and a little yachting cap such as Kino had seen once when a pleasure boat put into the estuary.

From "The Pearl" by John Steinbeck

Related Words

• inlet
• waterway