A fence or wattle placed in a stream to catch or retain fish.(noun)
A dam placed across a river or canal to raise or divert the water, as for a millrace, or to regulate or measure the flow.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "weir" in a sentence
"Is it possible for them to get through the weir from the bayou to the lake?"
"This measurement is obtained in several ways, among which probably the use of a weir is the simplest and most accurate, for small streams."
"This is what engineers call a weir, a handy contrivance for measuring the flow of small streams."