Source : Webster's Revised Unabridged Dictionary (1913)

Irreproachable \Ir`re*proach"a*ble\, a. [Pref. ir- not +
   reproachable: cf. F. irr['e]prochable.]
   Not reproachable; above reproach; not deserving reproach;
   blameless.

         He [Berkely] erred, -- and who is free from error? --
         but his intentions were irreproachable.  --Beattie.

Source : WordNet®

irreproachable
     adj : free of guilt; not subject to blame; "has lived a blameless
           life"; "of irreproachable character"; "an unimpeachable
           reputation" [syn: {blameless}, {inculpable}, {unimpeachable}]