Definition
An aeronautical beacon used to indicate the location of an aerodrome from the air. The [ICAO] tag means this definition follows the International Civil Aviation Organization's standard wording, which applies internationally rather than being specific to U.S. FAA usage.
Plain English
A light at an airport that flashes through the night sky so pilots flying overhead can spot the airport from a distance.
Context Anchor
Seen in airport lighting descriptions, night flying, and ICAO-based aviation references.
Derivation
Aerodrome comes from the Greek 'aero' (air) and 'dromos' (running track or course) -- literally a 'running place for aircraft.' Outside the U.S., 'aerodrome' is the common word for what Americans usually call an 'airport.' Beacon comes from Old English 'beacn,' meaning a signal or sign, often a fire lit on a hill to guide travelers. The aviation use keeps that same idea: a light that guides pilots to a known place.
Why Pilots Care
It lets pilots quickly confirm they have reached the correct airport at night, reducing the chance of landing at the wrong field or becoming disoriented among other lights.
Analogy
It works much like a lighthouse for aircraft: it does not land the airplane for you, but it helps you pick out the place you are looking for.
Intuition Check
Aerodrome does not mean only a large airline airport; it can mean an airport or other defined landing area. Beacon here means an aviation identification light, not just any bright light on the ground.
Example Sentence 1
Approaching the field after sunset, the crew picked up the aerodrome beacon flashing green and white about ten miles out.
Example Sentence 2
Per the AIM, aerodrome beacons operate from sunset to sunrise to support visual identification of the airport.