The Collaborative International Dictionary of English v.0.48:

Exonerate \Ex*on"er*ate\, v. t. [imp. & p. p. Exonerated; p.
   pr. & vb. n. Exonerating.] [L. exoneratus, p. p. of
   exonerare to free from a burden; ex out, from onerare to
   load, onus load. See Onerous.]
   1. To unload; to disburden; to discharge. [Obs.]
      [1913 Webster]

            All exonerate themselves into one common duct.
                                                  --Ray.
      [1913 Webster]

   2. To relieve, in a moral sense, as of a charge, obligation,
      or load of blame resting on one; to clear of something
      that lies upon oppresses one, as an accusation or
      imputation; as, to exonerate one's self from blame, or
      from the charge of avarice. --Burke.
      [1913 Webster]

   3. To discharge from duty or obligation, as a bail.

   Syn: To absolve; acquit; exculpate. See Absolve.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

exonerated \exonerated\ adj.
   same as exculpated.

   Syn: absolved, cleared, exculpated, vindicated.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

exonerated
    adj 1: freed from any question of guilt; "is absolved from all
           blame"; "was now clear of the charge of cowardice"; "his
           official honor is vindicated" [syn: absolved, clear,
           cleared, exculpated, exonerated, vindicated]