The term 'Instrument Held Between the Knees' can be summarized as a HARP, which is a four-letter word. A HARP is a stringed musical instrument that has a triangular frame and is held between the knees of the player. It is one of the oldest known instruments and has been used for centuries in many different cultures. The strings are plucked or strummed to produce sound. Harps come in many sizes and styles, from small lap harps to large concert harps.