Tesla coil

Century Dictionary and Cyclopedia

1. n. a form of transformer for the production of oscillatory currents of high frequency and high voltage. See transformer.

Wiktionary

1. n. A type of resonant transformer circuit used to produce high voltage, low current, high frequency alternating current electricity.

GNU Webster's 1913

1. (Elec.) A transformer without iron, for high frequency alternating or oscillating currents; an oscillation transformer.

WordNet 3.0

1. n. a step-up transformer with an air core; used to produce high voltages at high frequencies