Definition
The specific radio frequencies, expressed in megahertz, used to communicate with the air traffic control tower at a towered airport. Each towered airport publishes its own tower frequency (or frequencies, if more than one is in use), and pilots tune the aircraft radio to that frequency to receive taxi, takeoff, and landing instructions from the controller in the tower.
Plain English
The radio channels a pilot uses to talk to the control tower at an airport that has one. The pilot looks up the right number for that airport, tunes it in, and uses it to get permission to taxi, take off, and land.
Context Anchor
You see tower frequencies in airport information and use them before takeoff, before landing, or when operating near a runway at an airport with an operating control tower.
Derivation
Frequency comes from an older word meaning how often something happens. In radio use, it means the exact signal setting a radio uses so one station can hear another. Tower points to the airport control tower, where controllers direct traffic near the airport.
Why Pilots Care
Using the correct tower frequency lets pilots receive takeoff and landing clearances, traffic advisories, and immediate safety instructions.
Intuition Check
Do not read tower frequencies as a list about the physical tower building. In aviation, they are the radio channels used to talk with the controllers who manage runway and nearby airport traffic.
Example Sentence 1
About ten miles out, the student switched from the approach controller to the tower frequency and reported the field in sight.
Example Sentence 2
While flying the traffic pattern, the student pilot monitored the tower frequency for other aircraft calls.