A device for transposing a fretted string instrument such as the guitar. See also Barre.See Da capo. head; i.e., the beginning (of a movement, normally)lit. the head, the beginning<br><br>A mechanical barre that attaches to the neck of a guitar by means of a string, spring, elastic or nylon band, or a lever and thumbscrew arrangement. The capo can be used to raise the key of a song to suit a vocalist as well as to lower the action and shorten the string length