1. a low dam built across a river or stream to control the flow of water

Examples

• The old stone weir helped regulate water levels in the mill pond.
• Fish ladders were built alongside the weir to help salmon migrate upstream.
• The weir created a small waterfall that attracted many visitors.
• Engineers inspected the weir after the heavy spring floods.
• The medieval weir still functions to divert water to the irrigation channels.
• Local authorities plan to remove the damaged weir to restore natural river flow.