The Collaborative International Dictionary of English v.0.48:

Nonsuch \Non"such\, n.
   See Nonesuch.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nonsuch
    n 1: model of excellence or perfection of a kind; one having no
         equal [syn: ideal, paragon, nonpareil, saint,
         apotheosis, nonesuch, nonsuch]