Solenoid

noun

1. A current-carrying coil of wire that acts like a magnet when a current passes through it.
2. An assembly used as a switch, consisting of a coil and a metal core free to slide along the coil axis under the influence of the magnetic field.
3. A helix of copper or other conducting wire wound in the form of a cylinder so as to be nearly equivalent to a number of equal and parallel circular circuits arranged upon a common axis.
4. 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.
5. A coil of wire that acts as a magnet when an electric current flows through it