Source : Webster's Revised Unabridged Dictionary (1913)

Improbity \Im*prob"i*ty\, n. [L. improbitas; pref. im- not +
   probitas probity: cf. F. improbit['e].]
   Lack of probity; want of integrity or rectitude; dishonesty.

         Persons . . . cast out for notorious improbity.
                                                  --Hooker.