The Collaborative International Dictionary of English v.0.48:

Paranymph \Par"a*nymph\, n. [L. paranymphus, Gr. ?; para`
   beside, near + ? a bride: cf. F. paranymphe.]
   1. (Gr. Antiq.)
      (a) A friend of the bridegroom who went with him in his
          chariot to fetch home the bride. --Milton.
      (b) The bridesmaid who conducted the bride to the
          bridegroom.
          [1913 Webster]

   2. Hence: An ally; a supporter or abettor. --Jer. Taylor.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

101 Moby Thesaurus words for "paranymph":
   Maecenas, abettor, acolyte, adjutant, admirer, advocate,
   aficionado, agent, aid, aide, aide-de-camp, aider, alter ego,
   alternate, amicus curiae, angel, apologist, assistant, attendant,
   attorney, auxiliary, backer, backup, backup man, best man,
   bridemaiden, bridesmaid, bridesman, buff, champion, coadjutant,
   coadjutor, coadjutress, coadjutrix, defender, dependence, deputy,
   dummy, encourager, endorser, executive officer, exponent, fan,
   favorer, figurehead, friend at court, groomsman, help, helper,
   helpmate, helpmeet, lieutenant, locum, locum tenens, lover,
   mainstay, maintainer, matron of honor, paraprofessional, partisan,
   patron, pinch hitter, pleader, procurator, promoter, protagonist,
   proxy, reliance, representative, second, second in command,
   secondary, seconder, sectary, servant, sideman, sider, sponsor,
   stalwart, stand-in, standby, substitute, support, supporter,
   supporting actor, supporting instrumentalist, surrogate, sustainer,
   sympathizer, understudy, upholder, usher, utility man, vicar,
   vicar general, vice, vicegerent, votary, wedding attendant,
   wedding party, well-wisher