1. The phenomenon noticed by Aristotle whereby terms may apply in different, yet associated, ways, to different categories of thing: a place may be cheerful, and so may a person.

2. In the theory of types Russell had to postulate a systematic ambiguity linking the different meanings that expressions would have when used at different levels in the hierarchy, since it is clear that something is the same about the use, say, of the identity predicate when linking objects at one level, and at another.