Theorbo
in music, an old stringed instrument resembling the lute in form or tone. It had two necks, to the longest of which the bass strings were attached. It was employed for accompanying voices, and was in great favor during the 17th century. It differed from the lute in the possession of its two necks, whence it is sometimes called cithara bijuga. The strings were usually single in the theorbo, and when double, or tuned in octaves or in unison with the bass or treble notes, the instrument was called the arch lute or chittarone.