aqueduct

2. A channel or pipe built to carry water over long distances, often underground.

Engineers repaired the aqueduct that supplies water to the farms.

3. A small canal or tube in the body that carries fluid, such as in the brain.

The doctor explained how the aqueduct of Sylvius carries fluid in the brain.

4. A bridge-like structure that carries a canal over a river or valley.

Boats crossed the valley on a stone aqueduct.