The Collaborative International Dictionary of English v.0.48:

Ignore \Ig*nore"\, v. t. [imp. & p. p. Ignored; p. pr. & vb.
   n. Ignoring.] [L. ignorare; pref. in- not + the root of
   gnarus knowing, noscere to become acquainted with. See
   Know, and cf. Narrate.]
   1. To be ignorant of or not acquainted with. [Archaic]
      [1913 Webster]

            Philosophy would solidly be established, if men
            would more carefully distinguish those things that
            they know from those that they ignore. --Boyle.
      [1913 Webster]

   2. (Law) To throw out or reject as false or ungrounded; --
      said of a bill rejected by a grand jury for lack of
      evidence. See Ignoramus.
      [1913 Webster]

   3. Hence: To refuse to take notice of; to shut the eyes to;
      not to recognize; to disregard willfully and causelessly;
      as, to ignore certain facts; to ignore the presence of an
      objectionable person.
      [1913 Webster]

            Ignoring Italy under our feet,
            And seeing things before, behind.     --Mrs.
                                                  Browning.
      [1913 Webster]

WordNet (r) 3.0 (2006):

ignored
    adj 1: disregarded; "his cries were unheeded"; "Shaw's neglected
           one-act comedy, `A Village Wooing'"; "her ignored advice"
           [syn: ignored, neglected, unheeded]

Moby Thesaurus II by Grady Ward, 1.0:

62 Moby Thesaurus words for "ignored":
   abandoned, contemned, declined, declined with thanks, denied,
   deserted, despised, disapproved, discarded, discounted, disdained,
   dismissed, disowned, disregarded, excepted, excluded, forgotten,
   forsworn, half-done, ill-requited, ill-rewarded, laid aside,
   left undone, missed, neglected, not considered, omitted,
   overlooked, passed by, passed over, passed up, pigeonholed,
   put aside, rebuffed, refused, rejected, renounced, repudiated,
   repulsed, scouted, shunted, sidelined, sidetracked, slighted,
   spurned, unacknowledged, unasked, unattended to, uncared-for,
   unchaperoned, unconsidered, uncredited, undone, unfairly neglected,
   unrecognized, unregarded, unrequited, unrewarded, unsolicited,
   untended, unthanked, unwatched