beacon

Concise Oxford English Dictionary © 2008 Oxford University Press:
beacon/ˈbiːkən/

▶noun

• 1 a fire lit on the top of a hill as a signal.

• 2 a light serving as a signal for ships or aircraft.

• 3 a radio transmitter signalling the position of a ship or aircraft.

– origin OE bēacn ‘sign, portent, ensign’, of W. Gmc origin.