unmatched in WordNet English dictionary

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"
   matchless  nonpareil  one  one and only  peerless  unmatched  unmatchable  unrivaled  unrivalled 
   
2. of the remaining member of a pair, of socks e.g.
   odd  unmatched  unmated  unpaired 
   

unmatched in English Wiktionary