solenoid

noun4

1. •
   A coil of wire that acts as a magnet when an electric current flows through it.
2. •
   An electromechanical device consisting of such a coil containing a metal core, the movement of which is controlled by the current.
3. •
   An electromechanical switch controlled by a solenoid; solenoid switch, relay.
4. •
   The region of intersection between isobaric and isopycnal surfaces.