This chapter reviews phenomena suggesting that concepts like ‘bird’ or ‘game’ have a family resemblance structure, and the debates these phenomena have ignited concerning the meanings of linguistic labels (predicates) like
bird
and
game
. Conceptual semanticists have embraced family resemblance, modeling predicate meaning through mental conceptual representations, such as clusters of properties, prototypes, and similarity functions. To this end, they rejected classical logic as a basis for reasoning with natural language. By contrast, considering the advantages of classical logic, typically, formal semanticists have refrained from adopting the family resemblance view. Nonetheless, the chapter focuses on the less typical cases, where family resemblance structures are incorporated into referential semantic accounts assuming minimal deviation from classical logic (using the supervaluation technique). More recent nonclassical developments using vector semantics are briefly described as well.