EAVESDROP

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

To hear 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.