As a Noun: 1. A small plastic object with metal pieces which fit into the holes in a socket and connect the wire from a piece of electrical equipment to the electricity supply. English = plug. 2. A place on a wall or on a piece of electrical equipment into which you can put a plug. English = socket. As a Verb or Adjective: 1. To insert a plug into a socket. English = plug in. 2. Of a device or machine, to need to be plugged into an electric power source in order to operate. English = (be) electric, (be) powered by electricity.