The Collaborative International Dictionary of English v.0.48:

Disquisition \Dis`qui*si"tion\, n. [L. disquisitio, fr.
   disquirere to inquire diligently, investigate; dis- +
   quaerere to seek. See Quest.]
   A formal or systematic inquiry into, or discussion of, any
   subject; a full examination or investigation of a matter,
   with the arguments and facts bearing upon it; elaborate
   essay; dissertation.
   [1913 Webster]

         For accurate research or grave disquisition he was not
         well qualified.                          --Macaulay.
   [1913 Webster]

WordNet (r) 3.0 (2006):

disquisition
    n 1: an elaborate analytical or explanatory essay or discussion