noun
detector; locator
A device that detects or locates something, such as metal, gas, or submarines. Often used in compound nouns like 金属探知機 (metal detector).
空港で金属探知機を通った。
I passed through a metal detector at the airport.
この探知機はガス漏れを素早く見つける。
This detector quickly finds gas leaks.
Compound of 探知 (detection) + 機 (machine/device). The kanji 探 means 'search', 知 means 'know', and 機 means 'mechanism'.