radar
n. C / Un. a system that uses radio waves to find the position and speed of objects like planes or ships. You use it to see things that are far away or hidden by clouds.
n. a system for detecting the presence, direction, distance, and speed of aircraft, ships, and other objects, by sending out pulses of high-frequency electromagnetic waves that reflect off the object back to the source.
The pilot uses radar to navigate through the thick fog.
Air traffic controllers rely on sophisticated radar systems to maintain safe distances between planes during takeoff and landing.
Advanced meteorological radar allows scientists to track the internal structure of storm cells, providing critical data for early warning systems in regions prone to severe weather events.
Often used as a modifier before other nouns (e.g., 'radar equipment'). Frequently appears in the idiomatic phrase 'under the radar' to describe something done secretly or without notice.