A notion in prototype theory in which a particular member of a category can be assessed as to how well it reflects the prototype structure of the category it belongs to. This is achieved based on how many salient attributes belonging to the prototype the category member shares. The degree of overlap between shared attributes reflects a category member's degree of family resemblance. For instance, an ostrich cannot fly so lacks a salient attribute associated with the prototype structure of the category bird.

However, it shares other salient attributes, such as having a beak and wings. Thus it exhibits family resemblance but does not exhibit the same strength of family resemblance as a robin, for instance, which can fly.