Plain English Meaning
The radio channels pilots tune in to talk to towers, controllers, and other aircraft. Each one has a number, and you set that number on the radio to hear and be heard by the right people.
Full Definition
The specific channels, measured in megahertz (MHz), used by aircraft radios to transmit and receive voice communications with air traffic control, other aircraft, and ground stations. Each airport, control facility, and service is assigned its own frequency so that pilots and controllers can talk to the right party without interference from other transmissions.
Context Anchor
Pilots encounter radio frequencies during preflight planning, on charts and pages, and when setting up the radio before or during .