transformational-generative grammar, linguistic theory associated with Noam Chomsky, particularly with his Syntactic Structures (1957), and with Chomsky's teacher Zellig Harris. Generative grammar attempts to define rules that can generate the infinite number of grammatical (well-formed) sentences possible in a language. It starts not from a behaviorist analysis of minimal sounds but from a rationalist assumption that a deep structure underlies a language, and that a similar deep structure underlies all languages. Transformational grammar seeks to identify rules (transformations) that govern relations between parts of a sentence, on the assumption that beneath such aspects as word order a fundamental structure exists. Transformational and generative grammar together were the starting point for the tremendous growth in linguistics studies since the 1950s.