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 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

For most metals, TRI values were below 1, indicating no significant non-carcinogenic risk for adults consuming these foods from the Doce River estuary.

From Science Daily • Feb. 17, 2026

The estuary won, but the McCoys weren’t done.

From Los Angeles Times • Feb. 14, 2026

Van der Schatte Olivier said: "They show that, even in a dynamic estuary like this, we can successfully restore seagrass at scale when we use the right methods."

From BBC • Feb. 4, 2026

The estuary was not what anyone might call pristine rowing water even on the best of days.

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