Source : Webster's Revised Unabridged Dictionary (1913)

Dissertation \Dis`ser*ta"tion\, n. [L. dissertatio: cf. F.
   dissertation.]
   A formal or elaborate argumentative discourse, oral or
   written; a disquisition; an essay; a discussion; as,
   Dissertations on the Prophecies.

Source : WordNet®

dissertation
     n : a treatise advancing a new point of view resulting from
         research; usually a requirement for an advanced academic
         degree [syn: {thesis}]