Organ parts are essential components of an organ, a musical instrument that produces sound by driving air through pipes. The four organ parts in the crossword are keys (4 letters), PEDALS (6 letters), STOPS (5 letters), and pipes (5 letters). Keys are the buttons on the organ that are pressed to produce sound. PEDALS are the foot-operated levers that control the volume and pitch of the sound. STOPS are the knobs or buttons that control the flow of air to the pipes. Pipes are the tubes that produce sound when air is driven through them.