Meaning of Jew's harp

Jew's' harp"

Pronunciation: [key]
  1. (sometimes l.c.) 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.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.