to use one's head

use one thing for many purposes / work someone hard

(geometry, engineering) extended line (usually as an auxiliary line) / extension of a traffic route (e.g. highway or railway line) / (figuratively) extension or result developed from an existing thing

An extra game of soccer, baseball, martial arts, etc; an extra time; an extra innings.

mobile phone

teleportation

(education) instruction that takes place outside of a classroom (field trip, etc.) / (education) class that takes place in its own specialized room instead of homeroom (such as music or cooking)

moving average

a television station (building) / a television station (organization)

color television