The term 'Guitar Gadget' can be summarized as a CAPO, which is a four-letter device used to change the pitch of a guitar. It is typically attached to the neck of the guitar and held in place by the tension of the strings. The CAPO is used to raise the pitch of the strings, allowing the guitarist to play in different keys without having to retune the instrument. It is a popular tool among guitarists, as it allows them to quickly and easily switch between different keys.