In this book are entries introducing eighty ideas that have shaped the study of language up to the present day. Written by experts in the fields of linguistics and the philosophy of language, these entries reflect the full range of approaches and modes of thought. Each one includes a brief description of the idea, an account of its development, and an analysis of its impact on the field of language study. The book features clear descriptions of technical terms, guides to further reading, and extensive cross-referencing between entries. It also cross-references with "Key Thinkers in Linguistics and the Philosophy of Language (Edinburgh, 2005)," revealing significant connections and continuities in the two related disciplines. Ideas covered range from sense data, artificial intelligence, and logic to generative semantics, cognitivism, and conversation analysis, from political correctness to deconstruction and corpora.