The Collaborative International Dictionary of English v.0.48:

Irreprehensible \Ir*rep`re*hen"si*ble\, a. [L.
   irreprehensibilis: cf. F. irr['e]pr['e]hensible. See
   Reprehensible.]
   Not reprehensible; blameless; innocent. --
   Ir*rep`re*hen"si*ble*ness, n. -- Ir*rep`re*hen"si*bly,
   adv.
   [1913 Webster]