The aim of this paper is to show the Old-Iranian genesis of the term “duma” used to refer to the genre of Ukrainian folk epic. Research methodology. The research methodology applies historical and logical and comparative methods used for studying the interpretation the Ukrainian term “duma”, related to Old-Iranian and Old-Slavic worlds and used to define the genre of national epic tradition. Results. In the scientific literature, the “duma” epic is regarded as a late-stage phenomenon, without exploring its historical links to earlier autochthonous epic traditions that prevailed in the territory of Ancient Ukraine, particularly ancient Iran. The Ukrainian ethnomusicologists (S. Grytsa) argue for its artificial formation, introduced in the literary sources of the Romantic era. The article attempts to refute this common sense. It is hypothesized that the word duma, first mentioned in the written sources of Kyivan Rus, has ancient Iranian genesis. The ancient Iranian component has been studied sufficiently in the material and spiritual culture of Ukraine, but the results of this study rarely fall within the attention of musicologists and ethnomusicologists. In the culture of Ukrainians, iranisms have been preserved since the Scythian-Sarmatian until Kozachchyna era, a period of the duma genre flourishing.Since ancient times, the word duma functioned in ancient Iranian languages, including Tajik. It correlated with the dumb-, duma-root, which meant “a tail” (L.Gertsenberg), and preserved in the name of the folk epic instrument “dombra”, “dumbbrak” (literally — a tail/lamb fat-tail, by I. Vyzgo-Ivanova). The form of ancient instruments was determined by their ideological content. The sacred meaning of Aries (lamb) and individual parts of its body correlated with the idea of Farn (good, power, strength) as a symbol of royal power in ancient Iranians, including the Scythians, and was embodied in the form of a musical instrument. The Iranian-speaking Afghans still name the folk singers as dumas, and the Turkic-speaking Kazakhs, whose ancestors were Iranian-speaking Scythian-Saka tribes, until recently, used the similar word duany to name the divine seers, performers of epic cycles. The semantics of these words indicates that these were used in ancient Iranian vocabulary to refer to both carriers of epic traditions (duma) and their epic instruments (dumbra, domra) and repertoire. It testifies to the fact that the early Slavic tribes in the territory of Ancient Ukraine borrowed the word duma during the period of direct contacts and assimilation processes with the Iranian-speaking world, beginning with the Scythian-Sarmatian-Alan era. F. Kolessa, and subsequently S. Grytsa pointed out the connection of duma musical stylistics and music of the East, explaining “chromaticism” in thoughts by oriental influences. Based on archaeological, historical and contemporary ethnomusicological studies, it can be argued that the so-called East was located within the modern Ukrainian territory. Those cultural elements, which individual ethnomusicologists interpret in the context of “Eastern” influences, prevailed in ancient Ukrainian lands for centuries, and are still rooted in the culture of the Ukrainians. Novelty. The paper refutes the well established in the scientific literature notion of late origin of the word and term duma as the genre name of the Ukrainian epic tradition. Its ancient Iranian genesis, the connection of duma genre with the Ossetian Kadagi has been proved. The practical significance. The material in this article can be used in academic programs of university courses for cultural studies, art studies, instrumental studies and the study of the history of the Ukrainian epic tradition. A linguistic analysis of the term and genre duma makes it possible to conduct broader comparative studies on term functioning during the era of the Eurasian people, who have had long-lasting close contacts with the Scythian-Sarmato-Alan world in the past., Здійснено семантичний аналіз терміна дума, що використовується для означення жанру української епічної традиції, доведено його давньоіранське походження, зв’язок з жанрами давньоіранської епічної традиції та її носіями — думами, дуанами. Виявлено кореляцію думового епосу з осетинськими епічними піснями-переказами — кадагами, що пов’язані з сюжетами скіфо-осетинського епосу «Нарти». Доведено взаємозалежність терміна дума та найменувань епічних музичних інструментів домбрá, думбрáк.