The concept of modernity in the realm of Iranian dramatic literature—particularly among the early Qajar-era playwrights—was regarded as an essential and foundational concept. It was both the driving force behind the emergence of dramatic literature in Iran and a core premise within the content and structure of early plays. However, the presence and various manifestations of this concept were not consistently understood in a singular way by playwrights of the period. Rather, its meaning underwent semantic transformations in response to shifting socio-political contexts and the rise of new ideologies, such as those represented by the Democrat Party (Ejtemāʿiyūn-e ʿĀmmiyūn) and the Moderate Socialists (Ejtemāʿiyūn-e Eʿtedālīyūn) during the First and Second National Consultative Assemblies (Majles). Based on this premise, the present article seeks to examine the meaning of modernity in the thought and works of one of the most prominent Qajar-era dramatists, Mo’ayyed al-Mamalek Fekri Ershad. Through an analysis of both his dramatic and non-dramatic writings, and in light of his affiliation with the Moderate Socialists, this study aims to demonstrate that Fekri Ershad’s understanding of modernity signified such ideas as coercive authority, state-society solidarity, Islamic unity, the orderly Achaemenid state, the constitutional law of the Mashrūṭeh, and opposition to antiquated traditions. These meanings were deeply intertwined with the historical conditions of his time and reflected the ideological conflict between advocates and opponents of modernity. To elucidate these semantic dimensions—which represent the broader semantic field of the concept of modernity—this study employs historical semantics as its theoretical framework. As a key component of Reinhart Koselleck’s theory of conceptual history (Begriffsgeschichte), historical semantics provides a method for analyzing the layered meanings of concepts across historical contexts. It offers a suitable approach for interpreting the historically contingent meanings of modernity in Fekri Ershad’s intellectual and literary corpus. Notably, this research applies the principle of diachrony in historical semantics in order to more precisely uncover and conceptualize the semantic layers of this foundational term.