The Collaborative International Dictionary of English v.0.48:

Relevant \Rel"e*vant\ (-vant), a. [F. relevant, p. pr. of
   relever to raise again, to relieve. See Relieve.]
   1. Relieving; lending aid or support. [R.] --Pownall.
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   2. Bearing upon, or properly applying to, the case in hand;
      pertinent; applicable.
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            Close and relevant arguments have very little hold
            on the passions.                      --Sydney
                                                  Smith.
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   3. (Scots Law) Sufficient to support the cause.
      [1913 Webster]

WordNet (r) 3.0 (2006):

relevant
    adj 1: having a bearing on or connection with the subject at
           issue; "the scientist corresponds with colleagues in
           order to learn about matters relevant to her own
           research" [ant: irrelevant]