What if words aren`t signs at all? What if the forms we speak and hear are only the surface emissions of deeper identity structures? A Word is Not a Sign introduces System G, a bold rethinking of lexical identity. Instead of treating words as form-meaning pairs, the book argues that every lexical item is anchored in a well-a geometric identity object with its own internal architecture. The familiar word-forms we use every day are merely carriers, leaked from these wells into the linguistic surface. This shift explains why content words behave so differently from function words, why polysemy is structured rather than chaotic, and why the same form can appear as a noun, verb, or modifier without creating new lexical entries. Through formal definitions, cross-framework comparisons, and a detailed case study of English no/not, the book shows how System G predicts real linguistic patterns and offers a falsifiable research program. For linguists, philosophers of language, and computational researchers, this monograph provides a new way to think about what words are-and why they behave the way they do.