The term 'Large Percussion Instrument' can be broken down into three separate words: GONG (4 letters), KETTLEDRUM (10 letters), and TYMPANI (7 letters). A GONG is a large, metal, circular instrument that is struck with a mallet to produce a loud sound. A KETTLEDRUM is a large, cylindrical drum that is played with two sticks. It is also known as a timpani or a tympanum. Finally, TYMPANI are a type of KETTLEDRUM that is usually made of copper and has a membrane stretched across the top. All three of these instruments are used to create a loud, reverberating sound.