the GNU version of the Collaborative International Dictionary of English
n. The quality or state of being rational; rationality.
The Century Dictionary and Cyclopedia
n. The state of being rational, or consistent with reason.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. the quality of being consistent with or based on logic
Word Usage
"In order to prove that they are not, and to have the means of judging hereafter of the rationalness of my present judgments, I will record the grounds of my despondency."