A central theoretical term in transformational grammar, opposed to deep structure. The ‘surface structure’ of a sentence is the final stage in the syntactic representation of a sentence, which provides the input to the phonological component of the grammar, and which thus most closely corresponds to the structure of the sentence we articulate and hear. The standard view was that a grammar operates by generating a set of abstract deep structures, subsequently converting these underlying representations into surface structures by applying a set of transformational rules. An alternative conception related surface structure directly to a semantic level of representation, bypassing deep structure altogether. Later models introduce a modified notion known as S-structure. The term surface grammar is sometimes used as an information term for the superficial properties of the sentence.