Where does the word “eavesdropper” come from and What does eavesdropper mean?

The eighteenth-century jurist, Sir William Blackstone, really told the whole story:

“Eaves-droppers, or such as listen under walls or windows or the eaves of a house to hearken after discourse, and thereupon to frame slanderous and mischievous tales, are a common nuisance, and presentable,” he adds, “at the court leet.”

Regrettably, however, the old “court leet” having jurisdiction over such offenses has gone out of existence; eavesdroppers frame their “slanderous and mischievous tales” with impunity nowadays.