potential difference

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The amount of energy per unit charge needed to move a charged particle from a reference point to a designated point in a static electric field; voltage. Also called potential.

Wiktionary

1. n. the difference in potential energy between two points in an electric field; the difference in charge between two points in an electrical circuit; voltage

WordNet 3.0

1. n. the difference in electrical charge between two points in a circuit expressed in volts