This book tackles the problem of ascertaining what is a lexical item. Based on extensive corpus evidence, the author queries the role of words as fundamental units of semantic analysis. Notions such as 'word sense', 'polysemy' and 'disambiguation' are called into question. It is argued that mainstream phraseology has provided an insufficient account of the realm of multi-word choices. Accordingly, the ideas of 'idiom' and 'collocation' undergo revision in this work. The author comes up with an alternative proposal about what constitutes a unit of meaning and how the vocabulary is organized.