The Collaborative International Dictionary of English v.0.48:

Supervenient \Su`per*ven"ient\, a. [L. superveniens, p. pr.]
   Coming as something additional or extraneous; coming
   afterwards.
   [1913 Webster]

         That branch of belief was in him supervenient to
         Christian practice.                      --Hammond.
   [1913 Webster]

         Divorces can be granted, a mensa et toro, only for
         supervenient causes.                     --Z. Swift.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

24 Moby Thesaurus words for "supervenient":
   accessory, accidental, additional, adscititious, adventitious,
   appurtenant, ascititious, auxiliary, casual, circumstantial,
   collateral, contingent, extra, fortuitous, incidental, inessential,
   nonessential, secondary, subsidiary, superadded, superfluous,
   supplemental, supplementary, unessential