noun, plural es·tu·ar·ies.
  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.

Origin of estuary

1530–40; < Latin aestuārium channel, creek, inlet, equivalent to aestu(s) tide + -ārium -ary
Related formses·tu·ar·i·al [es-choo-air-ee-uh l] /ˌɛs tʃuˈɛər i əl/, adjective
Can be confuseddelta estuary Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for estuarial

Historical Examples of estuarial

  • The bulk of estuarial silt comes down the main river from the upper Basin.

    The Nation's River

    United States Department of the Interior

British Dictionary definitions for estuarial


noun plural -aries
  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
Derived Formsestuarial (ˌɛstjʊˈɛərɪəl), adjective

Word Origin for estuary

C16: from Latin aestuārium marsh, channel, from aestus tide, billowing movement, related to aestās summer
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for estuarial



1530s, from Latin aestuarium "a tidal marsh or opening," from aestus "boiling (of the sea), tide, heat," from PIE *aidh- "to burn" (see edifice). Related: Estuaries; estuarine.

Online Etymology Dictionary, © 2010 Douglas Harper

estuarial in Science


  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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

estuarial in Culture



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

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.