eavesdrop
verb

- to listen to someone's private conversation without them knowing

noun

- eavesdropping

(Cambridge Advanced Learner’s Dictionary)

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Eavesdrop is a compound word combining eaves and drop. Eaves (always plural) refer to the edge of a roof that hangs over the side of a building. The word "eaves" comes from the Old English "efes," meaning "edge of a roof."

The word drop in this context refers to "drip," which led to the Old English word "yfesdrype" or "eavesdrip," (which later became eavesdrop) which described the act of rainwater dripping over the eaves or the ground underneath.

In other words, at first eavesdrop had nothing to do with snooping and spying.

By the late fifteenth century, the verb eavesdrop became a backformation of the noun that took on the figurative sense of standing on the eavesdrop of a house to listen to what is happening inside.

Over time it came to mean listening to any conversation without the participants knowing or realizing it. These days, governments and hackers no longer have to stand under the eaves to listen in. All they need is Internet access.

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SYNONYMS

bug, listen in, monitor, overhear, pry, snoop, spy, tap, wiretap

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SMUGGLE OWAD into today's conversation

"Sometimes one can’t avoid eavesdropping on a crowded train."