The Collaborative International Dictionary of English v.0.48:

Probity \Prob"i*ty\, n. [F. probit['e], fr. L. probitas, fr.
   probus good, proper, honest. Cf. Prove.]
   Tried virtue or integrity; approved moral excellence;
   honesty; rectitude; uprightness. "Probity of mind." --Pope.
   [1913 Webster]

   Syn: Probity, Integrity.

   Usage: Probity denotes unimpeachable honesty and virtue,
          shown especially by the performance of those
          obligations, called imperfect, which the laws of the
          state do not reach, and can not enforce. Integrity
          denotes a whole-hearted honesty, and especially that
          which excludes all injustice that might favor one's
          self. It has a peculiar reference to uprightness in
          mutual dealings, transfer of property, and the
          execution of trusts for others.
          [1913 Webster]

WordNet (r) 3.0 (2006):

probity
    n 1: complete and confirmed integrity; having strong moral
         principles; "in a world where financial probity may not be
         widespread"; "he enjoys an exaggerated reputation for
         probity"

Moby Thesaurus II by Grady Ward, 1.0:

25 Moby Thesaurus words for "probity":
   angelicalness, decency, equity, fairness, godliness, goodness,
   honesty, honor, integrity, justice, justness, moral rectitude,
   morale, morality, rectitude, right conduct, righteousness,
   rightness, saintlikeness, saintliness, sincerity, trustworthiness,
   uprightness, virtue, virtuousness



Bouvier's Law Dictionary, Revised 6th Ed (1856):

PROBITY. Justice, honesty. A man of probity is one who loves justice and
honesty, and who dislikes the contrary. Wolff, Dr. de la Nat. Sec. 772.