Source : Webster's Revised Unabridged Dictionary (1913)

Contrabass \Con`tra*bass"\, n. (Mus.)
   The lowest stringed instrument of the violin family.

Contrabass \Con`tra*bass"\, n. (Mus.)
   Double bass; -- applied to any instrument of the same deep
   range as the stringed double bass; as, the contrabass
   ophicleide; the contrabass tuba or bombardon.

Source : WordNet®

contrabass
     adj : pitched an octave below normal bass instrumental or vocal
           range; "contrabass or double-bass clarinet" [syn: {double-bass}]
     n : largest and lowest member of the violin family [syn: {bass
         fiddle}, {bass viol}, {bull fiddle}, {double bass}, {string
         bass}]