This paper examines the vocabulary through which royal and sultanic authority was expressed, received, and negotiated in the context of the Ottoman/Polish-Lithuanian frontier in the sixteenth century. A failure to establish a mutually recognized border in 1542 and a sustained need for peaceful relations resulted in nearly a century of overlapping claims to territorial ownership. Consequently, the Polish-Lithuanian and Ottoman rule in the region was realized during this period by constantly renegotiating the personal authority of both sovereigns over the populations of their mutual, contested frontier. These negotiations took place in official documents that were issued by Ottoman and Polish-Lithuanian power brokers in a number of languages: Ottoman Turkish, Turkic Crimean vernacular, Italian, Polish, Latin, and Ruthenian. A mutually intelligible vocabulary was expressed simultaneously through these multiple languages and was quickly established in order to facilitate rivalling claims to personal authority in the frontier zone. By unpacking the multiple meanings of terms used to describe various frontier populations and their relationships with king and sultan, it is possible to re-examine seemingly incongruent episodes of codominium and parallel dominium in what was one of the longest Ottoman frontiers in Christian Europe.