The use of vague language (for example expressions such as 'bags of time', 'doing stuff', 'sort of thing', 'and all that') is an aspect of communicative competence of considerable social importance. Vague Language Explored examines the function of vague language in context. It spans genre analysis, critical discourse analysis, psycholinguistics and cross-cultural sociolinguistics, in a variety of world cultures. It suggests also applications in TEFL, asking questions such as 'What should learners be taught to understand and use, and why?' and suggesting directions for future research.