weir definition by Webster's New World
- a low dam built in a river to back up or divert water, as for a mill; milldam
- a fence, as of brushwood or stakes, built in a stream, channel, etc., for catching fish
- an obstruction placed in a stream, diverting the water through a prepared aperture for measuring the rate of flow
Origin: Middle English were ; from Old English wer, weir, dam (akin to German wehr) ; from base of werian, to defend, dam up ; from Indo-European base an unverified form wer-, to shut up, cover
weir definition by American Heritage Dictionary
- A fence or wattle placed in a stream to catch or retain fish.
- 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.
Origin: Middle English were, from Old English wer; see wer-4 in Indo-European roots.