Plain English Meaning
A shared radio frequency that pilots use to talk to each other at airports where no one in a tower is directing traffic. Everyone tunes to the same frequency and announces what they are doing so other pilots in the area know where they are.
Full Definition
A radio frequency designated for pilots to broadcast their position and intentions to other aircraft when operating at an airport without an active control tower. The CTAF may be a UNICOM, MULTICOM, FSS, or tower frequency, and is identified on aeronautical charts and in the Chart Supplement.
Context Anchor
Pilots see the CTAF listed in and use it before , , , or flying near that .