olemus
Wiktionary:
an electrical cord with a plug one end, and a single socket or a multi-port socket at the other end, used for powering one or more devices at a distance, too far from the wall outlet to be reached by the normal cords of the device or devices

näiteid
https://duckduckgo.com/?q=extension+cord&t=h_&iax=images&ia=images

ülevaateid
https://en.wikipedia.org/wiki/Extension_cord