noun
listening device; bug; wiretap
Refers to a covert electronic device used to eavesdrop on conversations. Can be a physical bug or a wiretap. Often used in contexts of surveillance or espionage.
警察は容疑者の部屋に盗聴器を仕掛けた。
The police planted a listening device in the suspect's room.
会議室に盗聴器が仕掛け
We checked whether a bug had been planted in the conference room.
盗聴 is the act of wiretapping or eavesdropping, while 盗聴器 is the physical device used for it.
Compound of 盗聴 (eavesdropping) and 器 (device). The spelling 盗聴機 uses 機 (machine) instead, with no difference in meaning.