According to truth-conditional pragmatics, a word may contribute an ad hoc concept to the proposition expressed, that is, something that differs from the concept the word encodes (the lexicalized concept). In relevance-theoretic lexical pragmatics, ad hoc concepts are treated like a species of concepts proper. Concepts as well as ad hoc concepts are taken to be atomic. Lexical pragmatic adjustment is conceived as the formation of an ad hoc concept that is narrower or broader in extension (or both) than the lexicalized concept involved. We argue that difference in extension should not be taken as the crucial feature of lexical pragmatics, since ad hoc concepts can have the same extension as the lexicalized concept. In contrast, we propose a positive view of ad hoc concepts as clusters of information poised to be used in inference. (Surprisingly, ad hoc concepts turn out not to be concepts at all.) The cluster account drops the assumption that ad hoc concepts are atomic and can therefore provide a satisfactory explanation of lexical pragmatic adjustment.