Source : Webster's Revised Unabridged Dictionary (1913)

Rationality \Ra`tion*al"i*ty\, n.; pl. {-ties}. [F.
   rationalit['e], or L. rationalitas.]
   The quality or state of being rational; agreement with
   reason; possession of reason; due exercise of reason;
   reasonableness.

         When God has made rationality the common portion of
         mankind, how came it to be thy inclosure? --Gov. of
                                                  Tongue.

         Well-directed intentions, whose rationalities will
         never bear a rigid examination.          --Sir T.
                                                  Browne.

Source : WordNet®

rationality
     n 1: the state of having good sense and sound judgment; "his
          rationality may have been impaired"; "he had to rely
          less on reason than on rousing their emotions" [syn: {reason},
           {reasonableness}]
     2: the quality of being consistent with or based on logic [syn:
         {rationalness}]