The ethnic self-consciousness of the Armenian ethnos, which passed the peak of ethnogenesis at the end of the first millennium BC, was ensured by the common origin, language and territory, common historical memory, continuity of state-political formations, cultural traditions and customs. Armenia is one of the oldest Christian states, and the Christianisation of the country in the early 4th century introduced a new cementing component into the Armenian identity. Wars with Mazdean Iran and later with the Muslim world, the struggle for fatherland and the struggle for faith cemented ethno-cultural and ethno-political identity. Armenia was one of the first countries to enter the Universal Church of the Christian East. Armenians participated in three Ecumenical Councils: the Council of Nicaea (325), the Council of Constantinople (381) and the Council of Ephesus (431), but did not attend the Fourth Council of Chalcedon (451) because of the war with Iran. The acts of the Council of Chalcedon, which reached Armenia much later, divided Armenians into two confessional directions — supporters and opponents of the Chalcedonian oros; the latter suspected in it hidden Nestorianism and did not recognise the supremacy of the Patriarch of Constantinople, while their opponents accused them of heresy. The emergence of Armenian writing in the early 5th century and the phenomenon of the «Golden Age» — the unprecedented rise of Armenian literature after the invention of the alphabet — determined for centuries the ethnic identity of Armenians, the unity of which was most universally and concretely reflected in the ethnic term «Armenian» (հայ, hay, ἀρμένιος). That is why the designation of the supporters of the Chalcedonian oros as Armenians-«Romaeans» and Armenians-«Georgians» did not find an adequate explanation for a long time. The term «Chalcedonian Armenians» was introduced in the early XX century by N. Y. Marr, as a designation of Armenians, called in the sources of XI–XV centuries «Romans» or «Ivirs», depending on their belonging to the Greek or Georgian Church. This hypothesis posed an important problem in Orientalism, caused continuous discussions and, accordingly, initiated further research. In recent decades, various aspects of the problem of the Chalcedonian Armenians (political, social, administrative, theological, polemical, historiographical) have attracted the attention of researchers; however, there is a range of issues that are unexplored or controversial. The term «Chalcedonite Armenians» proposed by N. Y. Marr instead of «Armenians-Romeans» and «Armenians-Ivirs» remained the most debatable issue for a long time. The aim of this paper is to clarify the content of the term «Chalcedonian Armenians» and, accordingly, the use of double ethnonyms in medieval sources, which served the emergence of this term in Modern times, i.e. to study the chronology and authorship of these sources.