The Collaborative International Dictionary of English v.0.48:

Viol \Vi"ol\, n. [F. viole; cf. Pr. viola, viula, Sp., Pg., &
   It. viola, LL. vitula; of uncertain origin; perhaps from L.
   vitulari to celebrate a festival, keep holiday, be joyful,
   perhaps originally, to sacrifice a calf (vitulus; cf.
   Veal). Cf. Fiddle, Vielle, 2d Viola, Violin.]
   [1913 Webster]
   1. (Mus.) A stringed musical instrument formerly in use, of
      the same form as the violin, but larger, and having six
      strings, to be struck with a bow, and the neck furnished
      with frets for stopping the strings.
      [1913 Webster]

            Me softer airs befit, and softer strings
            Of lute, or viol still, more apt for mournful
            things.                               --Milton.
      [1913 Webster]

   Note: The name is now applied as a general term to designate
         instruments of the violin kind, as tenor viol, bass
         viol, etc.
         [1913 Webster]

   2. (Naut.) A large rope sometimes used in weighing anchor.
      [Written also voyal, and voyal.] --Totten.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Voyol \Voy"ol\, n. (Naut.)
   (a) See Viol, 2.
   (b) The block through which a messenger passes. [Written also
       viol, and voyal.]
       [1913 Webster]

WordNet (r) 3.0 (2006):

viol
    n 1: any of a family of bowed stringed instruments that preceded
         the violin family

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "viol":
   baritone, bass viol, descant viol, rebec, tenor viol, treble viol,
   tromba marina, trumpet marine, vielle, viol family, viola bastarda,
   viola da braccio, viola da gamba, viola da spalla,
   viola di bordone, viola di fagotto, viola pomposa, violette



Easton's 1897 Bible Dictionary:

Viol
   Heb. nebel (Isa. 5:12, R.V., "lute;" 14:11), a musical
   instrument, usually rendered "psaltery" (q.v.)