John McHardy Sinclair has made major contributions to applied linguistics in three related areas: language in education, discourse analysis, and corpus-assisted lexicography. This article discusses the far-reaching implications for language description of this third area. The corpus-assisted search methodology provides empirical evidence for an original and innovative model of phraseological units of meaning. This, in turn, provides new findings about the relation between word-forms, lemmas, grammar, and phraseology. The article gives examples of these points, places Sinclair's work briefly within a tradition of empirical text analysis, and identifies questions which are currently unanswered, but where productive lines of investigation are not difficult to see: (1) linguistic-descriptive (can we provide a comprehensive description of extended phrasal units for a given language?) and explanatory (what explains the high degree of syntagmatic organization in language in use?), and (2) socio-psychological (how can the description of phrasal units of meaning contribute to a theory of social action and to a theory of the ways in which we construe the social world?).