This book is the first major cross-linguistic study of 'flexible words', i.e. words that cannot be classified in terms of the traditional lexical categories Verb, Noun, Adjective or Adverb. Flexible words can - without special morphosyntactic marking - serve in functions for which other languages must employ members of two or more of the four traditional, 'specialised' word classes. Thus, flexible words are underspecified for communicative functions...