Wordnet 3.0
NOUN (1)
1. 
 the doctrine that the application of a general term to various objects indicates the existence of a mental entity that mediates the application; 
The Collaborative International Dictionary of English v.0.48:
Conceptualism \Con*cep"tu*al*ism\, n. (Metaph.)
   A theory, intermediate between realism and nominalism, that
   the mind has the power of forming for itself general
   conceptions of individual or single objects. --Stewart.
   [1913 Webster]
WordNet (r) 3.0 (2006):
conceptualism
    n 1: the doctrine that the application of a general term to
         various objects indicates the existence of a mental entity
         that mediates the application