Source : Webster's Revised Unabridged Dictionary (1913)

Gallstone \Gall"stone`\, n.
   A concretion, or calculus, formed in the gall bladder or
   biliary passages. See {Calculus}, n., 1.

Source : WordNet®

gallstone
     n : a calculus formed in the gall bladder or its ducts [syn: {bilestone}]