The Collaborative International Dictionary of English v.0.48:

Guiltless \Guilt"less\, a.
   1. Free from guilt; innocent.
      [1913 Webster]

            The Lord will not hold him guiltless that taketh his
            name in vain.                         --Ex. xx. 7.
      [1913 Webster]

   2. Without experience or trial; unacquainted (with).
      [1913 Webster]

            Such gardening tools, as art, yet rude,
            Guiltless of fire, had formed.        --Milton.
      -- Guilt"less*ly, adv. -- Guilt"less*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

guiltless
    adj 1: free from evil or guilt; "an innocent child"; "the
           principle that one is innocent until proved guilty" [syn:
           innocent, guiltless, clean-handed] [ant: guilty]

Moby Thesaurus II by Grady Ward, 1.0:

34 Moby Thesaurus words for "guiltless":
   angelic, blameless, chaste, childlike, clean, clear, dovelike,
   exemplary, faultless, immaculate, in the clear, incorrupt,
   inculpable, innocent, irreproachable, lamblike, not guilty,
   offenseless, prelapsarian, pristine, pure, reproachless, righteous,
   sans reproche, sinless, unblamable, uncorrupted, undefiled,
   unfallen, unlapsed, untouched by evil, virtuous, with clean hands,
   without reproach