Definition
GNSS is the ICAO term for any worldwide position, velocity, and time determination system that uses one or more satellite constellations, an aircraft receiver, and an integrity-monitoring component, used to support navigation across all phases of flight. It is the generic, international term that covers individual systems such as GPS (United States), GLONASS (Russia), Galileo (European Union), and BeiDou (China), as well as augmentation systems built on top of them.
Plain English
GNSS is the worldwide name for any satellite-based navigation system that tells an aircraft where it is, how fast it is moving, and what time it is. GPS is one example of a GNSS, but there are others used by other countries.
Context Anchor
Seen in avionics manuals, instrument procedure notes, flight planning, and discussions of GPS-based navigation.
Derivation
Global = worldwide. Navigation = finding your way. Satellite = the spacecraft providing the signals. System = the whole package of satellites, receivers, and monitoring working together. The word "Global" matters here — it signals that this is the umbrella term covering all national satellite systems, not just the US GPS.
Why Pilots Care
It supplies accurate position data worldwide, enabling precise routes and approaches without dependence on ground-based navigation aids.
Intuition Check
GNSS does not mean GPS only. GPS is one satellite navigation system; GNSS is the broader category that can include GPS and other satellite systems.
Example Sentence 1
The approach chart noted that GNSS equipment was required, meaning any approved satellite navigation system — not GPS alone — would meet the requirement.
Example Sentence 2
Modern flight plans often specify GNSS-based routes that provide direct paths between waypoints.