Mark C. Baker investigates the fundamental nature of nouns, verbs, and adjectives. He claims that the various superficial differences found in particular languages have a single underlying source which can be used to provide better definitions of these "parts of speech". The new definitions are supported by data from languages from every continent. Baker's book argues for a formal, syntax-oriented, and universal approach to the parts of speech, as opposed to the functionalist, semantic, and relativist approaches that have dominated the subject.