The Collaborative International Dictionary of English v.0.48:

Archlute \Arch"lute\, Archilute \Arch"i*lute\, n. [Cf. F.
   archiluth, It. arciliuto.] (Mus.)
   A large theorbo, or double-necked lute, formerly in use,
   having the bass strings doubled with an octave, and the
   higher strings with a unison.
   [1913 Webster]