noun, noun or participle which takes 'suru', transitive verb
eavesdropping; tapping
Secretly listening to others' conversations, either directly or via devices.
隣の部屋の話を盗み聞きしてしまった。
I ended up eavesdropping on the conversation in the next room.
電話を盗み聞きするのは
Tapping a phone call is a crime.