Definition of "solenoid"

(physics) A coil of wire that acts as a magnet when an electric current flows through it.  examples

(engineering) An electromechanical device consisting of such a coil containing a metal core, the movement of which is controlled by the current.  examples

(electronics) An electromechanical switch controlled by a solenoid; solenoid switch, relay.  examples

(meteorology) The region of intersection between isobaric and isopycnal surfaces.