From The Collaborative International Dictionary of English v.0.48 :
Excogitation \Ex*cog`i*ta"tion\, n. [L. excogitatio: cf. F.
excogitation.]
The act of excogitating; a devising in the thoughts;
invention; contrivance.
[1913 Webster]
From WordNet (r) 3.0 (2006) :
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, excogitation, conception, design]