Estuary

n.	1.	A place where water boils up; a spring that wells forth.
	2.	A passage, as the mouth of a river or lake, where the tide meets the current; an arm of the sea; a frith. it to the sea was often by long and wide estuaries. - Dana.
a.	1.	Belonging to, or formed in, an estuary; as, estuary strata.

Noun

1.

estuary - the wide part of a river where it nears the sea; fresh and salt water mix

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