Definition and background:
A lute with an elongated neck to accommodate the longer strings necessary to produce bass notes. It had two pegboxes to accommodate the great number of strings, and the bass strings were unstopped. The instrument usually had 13 or 14 single or double courses of strings. The archlute was popular both in Italy and England during the Renaissance.
For more information on the music term "Archlute" check out these other resources:
Wikipedia - Glossary of Musical Terminology
Virginia Tech Multimedia Music Dictionary
ORB -- Medieval Music Glossary