or Jews' harp
(sometimes lowercase) a small, simple musical instrument consisting of a lyre-shaped metal frame containing a metal tongue, which is plucked while the frame is held in the teeth, the vibrations causing twanging tones.
Origin of Jew's harp
First recorded in 1585–95; perhaps jocular; earlier called Jew's trump
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019