<p>This essay explores synecdoche as an extended argumentative structure in Roman defenses of rhetoric. While contemporary scholarship often limits synecdoche to semantic substitution or distinguishes it from metonymy, theorists have recognized its potential as a form of argument. In Roman rhetoric, Quintilian describes synecdoche as both a trope of part-whole relations and a parallel argumentative form in <i>Institutio Oratoria</i> with comparable aims and lexical choices. This study examines how Roman rhetoricians, notably Quintilian and Cicero, employed synecdoche in extended arguments in defense of rhetoric. These arguments structured interconnected ideas such as categorical distinctions, hierarchical significance, and temporal sequence by employing synecdochal structures. By comparing ancient definitions and examples, this analysis reveals synecdoche’s capacity to organize complex argumentative discourse, offering a lens to scrutinize its structural and functional role.&#xa0;</p>