"electronic system for locating objects by means of radio waves," 1941, acronym (more or less) from radio detecting and ranging. The U.S. choice, it won out over British radiolocation. Figurative from 1950.
例文
1. It was yet another case where the human eye outperformed radar .
これはレーダーよりも肉眼で勝ったもう一つの例である。
2.The plane is used for electronic jamming and radar detection.
この飛行機は電子干渉とレーダー探査に使用されている。
3.The US crew fixed its radar on the Turkish ship.