- any of various systems or devices using reflected radio waves to locate fixed objects and track moving ones: a radar system typically consists of a transmitter, receiver, and display screen, and is used in navigation, air traffic control, meteorology, mapping, etc.
- a special ability to perceive, recognize, or find a particular kind of thing, behavior, etc.: a teacher's radar for plagiarism
Origin of radarra(dio) d(etecting) a(nd) r(anging)
on (or off) the (or someone's) radar screen
under the radar screen
- beyond someone's ability to notice or perceive
- not attracting someone’s attention; not making an impression on someone