in studies of categorization, the idea that a set of instances may form a category or give rise to a concept even though there is no single attribute common to all the instances: It is sufficient that each instance should have one or more attributes in common with one or more other instances. The members of the category that have the most attributes in common with other members are said to have the highest family resemblance. The category prototype will be based on those members with the highest family resemblance and the lowest resemblance to members of other categories. See also disjunctive concept.