Ear of Dionysius

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a kind of ear trumpet with a flexible tube; - named from the Sicilian tyrant, who constructed a device to overhear the prisoners in his dungeons.

See also: Ear

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in classic literature ?
D'Artagnan raised the three or four boards which made his chamber another ear of Dionysius, spread a carpet on the floor, went upon his knees, and made a sign to Mme.
The Latomia del Paradiso, once a stone quarry, has blossomed into a beautiful garden, and we walked through it to reach a S-shaped artificial cavern called the Ear of Dionysius (named by Caravaggio), partly because of the amazing acoustics inside the cavern.