Plain English Meaning
A built-in screen in the cockpit that shows the pilot information from the aircraft's own instruments and systems.
Full Definition
A cockpit screen that is part of the aircraft's installed avionics system, used to present flight, navigation, engine, or systems information to the pilot. Avionics displays are certified components of the aircraft and receive data directly from onboard sensors and equipment.
Context Anchor
Seen in Electronic Flight Bag discussions when comparing information shown on an EFB with information shown on installed cockpit displays.
Derivation
Avionics is a blend of aviation and electronics, coined in the 1940s for electronic equipment built into aircraft. So an avionics display is, literally, an aircraft-electronics screen — installed in the panel rather than carried into the cockpit.