English▸ verb
(eavesdrops, eavesdropping, eavesdropped)
[no object] secretly listen to a conversation: she opened the window just enough to eavesdrop on the conversation outside.
– ORIGIN early 17th century : back-formation from eavesdropper (late Middle English) ‘a person who listens from under the eaves’, from the obsolete noun eavesdrop ‘the ground on to which water drips from the eaves’, probably from Old Norse upsardropi, from ups ‘eaves’ + dropi ‘a drop’.