The Collaborative International Dictionary of English v.0.48:

Triumphant \Tri*um"phant\, a. [L. triumphans, p. pr. of
   triumphare: cf. F. triomphant. See Triumph, v. i.]
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   1. Rejoicing for victory; triumphing; exultant.
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            Successful beyond hope to lead ye forth
            Triumphant out of this infernal pit.  --Milton.
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   2. Celebrating victory; expressive of joy for success; as, a
      triumphant song or ode.
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   3. Graced with conquest; victorious.
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            Athena, war's triumphant maid.        --Pope.
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            So shall it be in the church triumphant. --Perkins.
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   4. Of or pertaining to triumph; triumphal. [Obs.]
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            Captives bound to a triumphant car.   --Shak.
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   Church triumphant, the church in heaven, enjoying a state
      of triumph, her warfare with evil being over; --
      distinguished from church militant. See under
      Militant.
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WordNet (r) 3.0 (2006):

triumphant
    adj 1: joyful and proud especially because of triumph or
           success; "rejoicing crowds filled the streets on VJ Day";
           "a triumphal success"; "a triumphant shout" [syn:
           exultant, exulting, jubilant, prideful,
           rejoicing, triumphal, triumphant]
    2: experiencing triumph [syn: triumphant, victorious]