eavesdrop

verb

Pronunciation: /ˈiːvzˌdɹɒp/ / /ˈivzˌdɹɑp/

Etymology: From eaves + drop; the "listening" sense derives from the notion of the listener standing in the area denoted by the physical sense.

The dripping of rain from the eaves of a house.
The space around a house on which such water drips.
A concealed aperture through which an occupant of a building can surreptitiously listen to people talking at an entrance to the building.
The act of intentionally hearing a conversation not intended to be heard.
“Were you having a little eavesdrop on us last night?”

Etymology: From eaves + drop; the "listening" sense derives from the notion of the listener standing in the area denoted by the physical sense.

To hear (intentionally) a conversation one is not intended to hear; to listen in.
“I hope nobody was eavesdropping on our conversation last night, since it got so personal.”
To listen for another organism's calls, so as to exploit them.
“[…] Eastern Red Bat will eavesdrop on the sonar calls of other red bats to locate potential insect prey.”
“Frog-biting midges also depend on eavesdropping for reproduction, and one would predict similarly strong selection to evolve auditory adaptations for hearing and localizing calls of their hosts.”