Weir (noun)

1. A low dam built across a river or stream to raise the water level or divert its flow.
2. A fish trap that is placed in a stream or river, typically made of wood or stone.

Origin:

Derived from old english "wer", from proto-germanic "wēr" meaning dam or barrier.

Examples:

1. The weir was built to control the water flow and prevent flooding.
2. The weir was home to a large number of fish, which made it a popular spot for anglers.
3. The weir was used to generate hydroelectric power by harnessing the energy of the river.
4. The weir is an important structure for the local ecosystem, providing habitat for fish and other aquatic life.
5. The weir is an ancient structure, dating back to the Roman era.