Source : Webster's Revised Unabridged Dictionary (1913)

Thesis \The"sis\, n.; pl. {Theses}. [L., fr. Gr. ?, fr. ? to
   place, set. See {Do}, and cf. {Anathema}, {Apothecary},
   {Epithet}, {Hypothesis}, {Parenthesis}, {Theme}, {Tick} a
   cover.]
   1. A position or proposition which a person advances and
      offers to maintain, or which is actually maintained by
      argument.

   2. Hence, an essay or dissertation written upon specific or
      definite theme; especially, an essay presented by a
      candidate for a diploma or degree.

            I told them of the grave, becoming, and sublime
            deportment they should assume upon this mystical
            occasion, and read them two homilies and a thesis of
            my own composing, to prepare them.    --Goldsmith.

   3. (Logic) An affirmation, or distinction from a supposition
      or hypothesis.

   4. (Mus.) The accented part of the measure, expressed by the
      downward beat; -- the opposite of arsis.

   5. (Pros.)
      (a) The depression of the voice in pronouncing the
          syllables of a word.
      (b) The part of the foot upon which such a depression
          falls.

Source : WordNet®

thesis
     n 1: an unproved statement put forward as a premise in an
          argument
     2: a treatise advancing a new point of view resulting from
        research; usually a requirement for an advanced academic
        degree [syn: {dissertation}]
     [also: {theses} (pl)]