Longman Dictionary of Contemporary English
Wiktionary
n. 1 (context aviation English) An airport building from which the air traffic control unit monitors and directs the movement of aircraft on and around the airport. 2 An enclosed, raised structure occupied by one or more persons who operate or exercise control over railway traffic, ship movement, a racetrack, machinery, etc.
WordNet
n. a tower with an elevated workspace enclosed in glass for the visual observation of aircraft around an airport
Usage examples of "control tower".
The generator, apparently hastefully installed at the side of what had once been an airfield control tower, gave one last wheeze as a stanchion collapsed.
This looked slightly like a small airfield control tower, two storeys high with a glass-walled room at the top.
Blake ran up to the control tower to warn the B-17s that were due in and he eventually managed to land them safely.
The control tower demanded to know who had overridden the instructions.