Corpus linguistics prompts a lexicocentric approach to linguistic theory. The theory of norms and exploitations (TNE; Hanks, forthcoming) is such a theory, applying the insights of prototype theory and Sinclairian text analysis to the empirical evidence of large corpora. By studying words in context, we can identify the normal patterns of usage that are associated with each word. A meaning, or meaning potential, can then be associated with each pattern. Thereby, lexical entropy is reduced. A central question in this approach to language analysis concerns metaphors and idioms. In the present paper, conventional metaphors and idioms are classified as ‘norms’ (i.e. conventional uses), while dynamic, ad-hoc metaphors are classified as ‘exploitations’ of norms. However, conventional metaphors can still be distinguished from literal meanings. At least in some cases, conventional metaphors differ from literal senses by their particular syntagmatic patterns. The paper also discusses the importance of text type and domain in achieving a satisfactory interpretation of idiomatic expressions.