Source : Webster's Revised Unabridged Dictionary (1913)

Sophist \Soph"ist\, n. [F. sophiste, L. sophistes, fr. Gr. ?.
   See {Sophism}.]
   1. One of a class of men who taught eloquence, philosophy,
      and politics in ancient Greece; especially, one of those
      who, by their fallacious but plausible reasoning, puzzled
      inquirers after truth, weakened the faith of the people,
      and drew upon themselves general hatred and contempt.

            Many of the Sophists doubdtless card not for truth
            or morality, and merely professed to teach how to
            make the worse appear the better reason; but there
            scems no reason to hold that they were a special
            class, teaching special opinions; even Socrates and
            Plato were sometimes styled Sophists. --Liddell &
                                                  Scott.

   2. Hence, an impostor in argument; a captious or fallacious
      reasoner.

Source : WordNet®

Sophist
     n 1: any of a group of Greek philosophers and teachers in the 5th
          century BC who speculated on a wide range of subjects
     2: someone whose reasoning is subtle and often specious [syn: {casuist}]