Solenoid

n.

1.

(Elec.) An electrodynamic spiral having the conjuctive wire turned back along its axis, so as to neutralize that component of the effect of the current which is due to the length of the spiral, and reduce the whole effect to that of a series of equal and parallel circular currents. When traversed by a current the solenoid exhibits polarity and attraction or repulsion, like a magnet.

Noun

1.

solenoid - a coil of wire around an iron core; becomes a magnet when current passes through the coil

coil, magnet