/ ˈreɪdɑː(r); NAmE / noun
[ U ] a system that uses radio waves to find the position and movement of objects, for example planes and ships, when they cannot be seen :
They located the ship by radar.
a radar screen
- on / off the radar screen
—more at bubble verb
1940s: from ra(dio) d(etection) a(nd) r(anging) .