The Oxford Thesaurus An A-Z Dictionary of Synonyms - extensive adj.

1) broad, wide, expansive, far-reaching, far-ranging, wide-ranging, far-flung, sweeping, widespread, comprehensive, all-embracing; national, nationwide, international, intercontinental, cosmopolitan, worldwide, global, universal, vast; cosmic; catholic: The storm is responsible for extensive crop damage. He has extensive business connections. 2) large, big, great, huge, substantial, considerable, sizeable, immense, enormous, vast, gigantic, massive; voluminous, spacious, commodious, capacious: The extensive gold deposits were soon depleted. The cave contains several extensive chambers.