Source : Webster's Revised Unabridged Dictionary (1913)

Solver \Sol"ver\ (s[o^]lv"[~e]r), n.
   One who, or that which, solves.

Source : WordNet®

solver
     n : a thinker who focuses on the problem as stated and tries to
         synthesize information and knowledge to achieve a
         solution [syn: {problem solver}, {convergent thinker}]