The Prototype is what a Stereotype is called in cognitive linguitics. It is an Idealized cognitive model (ICM) of reality which is used as a benchmark when categorizing objects and ideas.
It was coined by Eleanor Rosch in the 1970s as she performed experimental research in categorization. It was established that the categorization done by the subjects did not ressemble the traditional Aristotelian view with necessary and sufficient condition.
On the contrary it was discovered that there were typical members of a category and less typical members.
Influence
The Prototype theory has led to several new approaches in linguistics, such as Conceptual metaphors, Primary metaphors and Conceptual integration (or Blending).