The Collaborative International Dictionary of English v.0.48:

Supereminent \Su`per*em"i*nent\, a. [L. supereminens, p. pr. of
   supereminere. See Super-, and Eminent.]
   Eminent in a superior degree; surpassing others in
   excellence; as, a supereminent divine; the supereminent glory
   of Christ. -- Su`per*em"i*nent*ly, adv.
   [1913 Webster]