<p>Scientific terms and concepts sometimes evolve so that their semantic meanings are changing, to better serve the purposes of their use in scientific practices. Acknowledging the importance of such a process provides a viewpoint on the role of wave-particle duality (WPD) in modern quantum optics and how it is connected to its historical role. The transformation of WPD into a quantitative and operationalised concept is approached here from the viewpoint of the role of WPD as a linguistic practice based on natural language in communicating about experiments and their results and designs. The perspective adopted is based on semantic change and variation of WPD as driven by its role as natural language expression in pursuing the epistemic and the pragmatic goals of the inquiry. This provides a perspective that connects the historical and contemporary roles of WPD through its pragmatic linguistic role. This perspective shifts the focus from philosophical realism-driven questions about WPD as related to the nature or behaviour of photons to questions of how that concept is used in practices of quantum optics research, for what purposes, and with what benefits.</p>