1. An obstruction in a drill hole above the bottom of the hole usually formed by caving. Bridges block the passage of drilling tools or loading an explosive charge in a borehole. A bridge plug may be set deliberately. 2. An electrical network usually having four or more arms connected in a diamond arrangement and containing one branch (the ‘‘bridge’’) that connects two points of equal potential when the circuit is properly balanced; see Figure B-8. A Wheatstone bridge used for measuring electrical impedance. 3. A jumper or wire used to short-circuit around parts of an electrical circuit.