I suddenly wondered about the origin of the word eavesdrop, and as I started to look it up it occurred to me that it surely had to do with ‘eaves’ as in the eaves of a house. I don’t know why I didn’t make the connection immediately. Did I once know this and then lost the connection by familiarity?
Etymonline says the word means to “lurk near a place to hear what is said inside,” and dates from around 1600, and is probably a back-formation from eavesdropper. The original notion is listening from under the eaves of a house, originally yfesdrype the place around a house where the rainwater drips off the roof. So eaves is a shortening of a word that included ‘drype’ - presumably as in the dripping of water.
Eave or yfes comes from Old English efes meaning the edge of something.