Dictionary.net

[L.] The followers of John Roscelin, of Compiegne, who, in the eleventh century, asserted that general terms have no corresponding reality, being mere words or names and nothing more. This doctrine caused great alarm among the Schoolmen, who had thus far believed that all that was real in nature depended on those general notions which described their essences. Roscelin was compelled to retract his opinions ; but they were taken up by Abelard, who went with a body of his followers to Paris, and brought about the founding of the celebrated university in that city. The next Nominalist after Abelard was William of Ockham, who may be styled a Conceptualist, since he allowed to general terms a kind of subjective reality, as the signs of an actual process of thought, although they were neither distinct objects of consciousness nor realities in nature. Those who affirm that they are neither and deny to them this subjective reality, are Realists. See Schoolmen.