Nominalism, the name given to the theory of those among the Scholastics who maintained that general notions, which we denote by general terms, are only names, empty conceptions without reality, that there was no such thing as pure thought, only conception and sensuous perception, whereas realists, after Plato, held by the objective reality of universals. And, indeed, it is not as modern philosophy affirms, in the particular or the individual, in which alone, according to the Nominalists, reality resides, but in the universal, in regard to which the particular is nothing if it does not refer.
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
Nollekens, Joseph * Nonconformists