- a rule that converts one phrase marker into another. Taken together, these rules, which form the transformational component of the grammar, convert the deep structures of sentences into their surface structures
WordReference Random House Unabridged Dictionary of American English © 2015
[Ling.]a rule of transformational grammar that relates two phrase markers in the course of a derivation from the deep to the surface syntactic representation of a sentence, as by reordering, inserting, or deleting elements;
a rule that converts deep structures into surface structures.