Source : Webster's Revised Unabridged Dictionary (1913)

Excogitation \Ex*cog`i*ta"tion\, n. [L. excogitatio: cf. F.
   excogitation.]
   The act of excogitating; a devising in the thoughts;
   invention; contrivance.

Source : WordNet®

excogitation
     n 1: thinking something out with care in order to achieve
          complete understanding of it
     2: the creation of something in the mind [syn: {invention}, {innovation},
         {conception}, {design}]