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]