1. The unobstructed vertical distance between the lowest opening of a faucet (or the like) which supplies a plumbing fixture (such as tank or wash bowl) and the level at which the fixture will overflow.
2. In a drainage system, the unobstructed vertical distance between the outlet of a waste pipe and the flood-level rim of the receptacle into which it discharges.
3. A gap in an electric or magnetic circuit; usually acts as a high-resistance path in the circuit.
