radar

Từ điển Oxford Advanced Learner 8th

radar [radar radars] BrE [ˈreɪdɑː(r)] NAmE [ˈreɪdɑːr] noun uncountable
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
compare ↑sonar
more at bubble under the radar at ↑bubble _v.
Idioms: ↑below the radar ▪ ↑on the radar screen

Word Origin:
1940s: from ra(dio) d(etection) a(nd) r(anging).

Example Bank:
•The aircraft suddenly went off the radar.
•The submarine is impossible to detect on radar.
•navigating by radar
•navigation by radar

• Từ đồng nghĩa / Synonyms:
  microwave radar, radio detection and ranging, radiolocation