nominalist

from WordNet (r) 3.0 (2006)

nominalist
    n 1: a philosopher who has adopted the doctrine of nominalism

from The Collaborative International Dictionary of English v.0.48

Nominalist \Nom"i*nal*ist\, n. (Metaph.)
   One of a sect of philosophers in the Middle Ages, who adopted
   the opinion of Roscelin, that general conceptions, or
   universals, exist in name only. --Reid.
   [1913 Webster]