A canal is an artificial waterway constructed to allow the passage of boats or ships inland of convey water for irrigation. A lock is a short confined section of a canal or other waterway in which the water level can be changed by the use of gates and sluices, used for raising and lowering vessels between two grates.
Sentence:
A lock is used to move boats through a canal by moving the water level higher or lower to make it to the other side of a dam or slope that is too steep for the boat to go over itself.
