1. 
[syn: matchless, nonpareil, one(a), one and only(a), peerless, unmatched, unmatchable, unrivaled, unrivalled]
The Collaborative International Dictionary of English v.0.48:
Unrivaled \Un*ri"valed\, a.
   Having no rival; without a competitor; peerless. [Spelt also
   unrivalled.] --Pope.
   [1913 Webster]
WordNet (r) 3.0 (2006):
unrivalled
    adj 1: eminent beyond or above comparison; "matchless beauty";
           "the team's nonpareil center fielder"; "she's one girl in
           a million"; "the one and only Muhammad Ali"; "a peerless
           scholar"; "infamy unmatched in the Western world"; "wrote
           with unmatchable clarity"; "unrivaled mastery of her art"
           [syn: matchless, nonpareil, one(a), one and
           only(a), peerless, unmatched, unmatchable,
           unrivaled, unrivalled]