Combining Signs in Sign-Based Construction Grammar: What’s in an Idiom?

This article revisits Charles Fillmore’s vision of the lexicon as the control center of grammar, advancing the claim that idioms are ordinary linguistic objects. Within Sign-Based Construction Grammar (SBCG), idiomatic expressions – whether fixed phrases, idiomatically combining forms, or formal idioms – are modeled as typed feature structures licensed by lexical entries and constructions. This unified architecture dissolves the traditional boundary between words and rules; in it, idioms occupy distinct points along a continuum of lexical fixity rather than standing outside the grammar. Through analyses of fixed expressions like in the know , idiomatically combining forms such as causative have , and formal idioms like the Split Interrogative, the paper demonstrates how SBCG integrates idiomaticity into a general theory of sign combination, fulfilling Fillmore’s goal of a grammar grounded in the structure of the lexicon.