Radar and Watchtower

Radar noun - Measuring instrument in which the echo of a pulse of microwave radiation is used to detect and locate distant objects.

Watchtower and radar are semantically related. In some cases you can use "Watchtower" instead a noun "Radar".

Watchtower noun - An observation tower for a lookout to watch over prisoners or watch for fires or enemies.

Radar and watchtower are semantically related. Sometimes you can use "Radar" instead a noun "Watchtower".