from
The Collaborative International Dictionary of English v.0.48
Improbable \Im*prob"a*ble\, a. [L. improbabilis; pref. im- not +
probabilis probable: cf. F. improbable. See {Probable}.]
Not probable; unlikely to be true; not to be expected under
the circumstances or in the usual course of events; as, an
improbable story or event.
[1913 Webster]
He . . . sent to Elutherius, then bishop of Rome, an
improbable letter, as some of the contents discover.
--Milton.
-- {Im*prob"a*ble*ness}, n. -- {Im*prob"a*bly}, adv.
[1913 Webster]