A place where water boils up; a spring that wells forth. Boyle. [1913 Webster]
A passage, as the mouth of a river or lake, where the tide meets the current; an arm of the sea; a frith. [1913 Webster]
"it to the sea was often by long and wide estuaries." [1913 Webster]

estuary, a.

Belonging to, or formed in, an estuary; as, estuary strata. Lyell. [1913 Webster]

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OXFORD DICTIONARY

estuary, n. (pl. -ies) a wide tidal mouth of a river.

Derivative

estuarine adj.

Etymology

L aestuarium tidal channel f. aestus tide

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THESAURUS

estuary

arm, armlet, avenue, bay, bayou, belt, bight, blowhole, boca, channel, chute, cove, creek, debouch, door, egress, emunctory, escape, euripus, exhaust, exit, fjord, floodgate, flume, frith, gulf, gut, harbor, inlet, kyle, loch, loophole, mouth, narrow, narrow seas, narrows, natural harbor, opening, out, outcome, outfall, outgate, outgo, outlet, pore, port, reach, road, roads, roadstead, sally port, sluice, sound, spiracle, spout, strait, straits, tap, vent, ventage, venthole, vomitory, way out, weir

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ROGET THESAURUS

estuary

Lake

N gulf, lake, land covered with water, gulf, gulph, bay, inlet, bight, estuary, arm of the sea, bayou, fiord, armlet, frith, firth, ostiary, mouth, lagune, lagoon, indraught, cove, creek, natural harbor, roads, strait, narrows, Euripus, sound, belt, gut, kyles, continental slope, continental shelf, lake, loch, lough, mere, tarn, plash, broad, pond, pool, lin, puddle, slab, well, artesian well, standing water, dead water, sheet of water, fish pond, mill pond, ditch, dike, dyke, dam, reservoir, alberca, barachois, hog wallow, lacustrine.

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