The term 'Mandolin's Ancestor' can be summarized as the LUTE, which is a four-letter word. The LUTE is a stringed instrument that has been around since ancient times and is considered to be one of the oldest instruments in the world. It is believed to have originated in the Middle East and was popularized in Europe during the Renaissance period. The LUTE is the ancestor of many modern stringed instruments, including the mandolin.