Plain English Meaning
A network of satellites that lets a receiver figure out exactly where it is, how fast it is moving, and the precise time, by listening to signals from several satellites at once.
Full Definition
A satellite-based radio navigation system operated by the United States that provides position, velocity, and precise time information to suitably equipped users anywhere on or near the Earth. It uses a constellation of satellites in medium Earth orbit transmitting timed signals; a receiver calculates its own three-dimensional position by measuring the time it takes signals to arrive from at least four satellites.
Context Anchor
Pilots encounter this term when using panel-mounted GPS units, moving-map displays, route navigation, and some instrument procedures.