estuary

noun

es·​tu·​ary ˈes-chə-ˌwer-ē 

ˈesh-

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

Did you know?

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.

Synonyms of estuary

• bay
• firth

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

But these sites also come with dangers, as demonstrated by the massive Moss Landing battery fire in January 2025, which prompted the evacuation of about 1,500 residents and deposited heavy metals in a nearby estuary. — Clara Harter, Los Angeles Times, 25 Sep. 2026

Visitors traveling across Rhode Island’s Narragansett Bay earlier this month may have seen a strange-looking boat with wings and a whale-like tail floating in the estuary’s calm late-summer waters. — Mack Degeurin, Popular Science, 23 Sep. 2026

The bay facing the western shore of Newfoundland is the mouth—the gaping estuary—of the Saint Lawrence, Newfoundland on the chart detached and apparently drifting out to sea. — Paul Theroux, Condé Nast Traveler, 22 Sep. 2026

The original measure, known as Executive Order 13508, was designed to improve protection and restoration efforts for the Chesapeake Bay, the largest estuary in the United States. — Bryan Lynn, CBS News, 17 Sep. 2026

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

Rhymes for estuary

• askari
• astbury
• azeri
• banbury
• barberry
• blackberry
• blueberry
• canary
• cranberry
• dentary
• dewberry
• dogberry

Kids Definition

estuary

noun

es·​tu·​ary ˈes-chə-ˌwer-ē 

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