Eighteenth-century English grammarians plead eloquently for purity, precision and perspicuity, but their method of teaching largely amounts to citing examples of impurity, imprecision and lack of clarity from contemporary writings. This book is the first of its kind to provide a detailed systematic account of such 'errors'. Apart from source and page references, the Dictionary gives the context of the error (I have not wept this forty years), the correct or 'target' form ('these forty years'), the name of the authors quoted by the grammarians ('Addison', 'Swift'), and the labels which sum up their assessment of the error ('absurd', 'solecism'). It operates with error categories such as ambiguity, ellipsis and government (fourteen in all), which are subdivided into grammatically described main entries, subentries, and so on. The Introduction includes a guide to the use of the Dictionary, the grammatical code, and a discussion of grammatical concepts, error typologies, problems of identifying literary sources, attitudes to correctness, grammatical figures, and other topics. A Bibliography and an Index of lexical items and technical terms round off the volume. The way the Dictionary is organized should make it possible to find in it the answer to a wide variety of questions pertaining to grammar, style and linguistic historiography.