Ruthenian (ру́скаꙗ мо́ва or ру́скїй ѧзы́къ;^{[1][2][failed verification]} see also other names) is an exonymic linguonym for a closely related group of East Slavic linguistic varieties, particularly those spoken from the 15th to 18th centuries in the Grand Duchy of Lithuania and in East Slavic regions of the Polish–Lithuanian Commonwealth. Regional distribution of those varieties, both in their literary and vernacular forms, corresponded approximately to the territories of the modern states of Belarus and Ukraine. By the end of the 18th century, they gradually diverged into regional variants, which subsequently developed into the modern Belarusian, Ukrainian, and Rusyn languages, all of which are mutually intelligible. ^[5][6][7][8]

Several linguistic issues are debated among linguists: various questions related to classification of literary and vernacular varieties of this language; issues related to meanings and proper uses of various endonymic (native) and exonymic (foreign) glottonyms (names of languages and linguistic varieties); questions on its relation to modern East Slavic languages, and its relation to Old East Slavic (the colloquial language used in Kievan Rus' in the 10th through 13th centuries).^[9]

Since the term Ruthenian language was exonymic (foreign, both in origin and nature), its use was very complex, both in historical and modern scholarly terminology.^[11]

Contemporary names, that were used for this language from the 15th to 18th centuries, can be divided into two basic linguistic categories, the first being endonyms (native names, used by native speakers as self-designations for their language), and the second exonyms (names in foreign languages).

Common endonyms:

• Ruska(ja) mova, written in various ways, as: ру́скаꙗ мо́ва, and also as: ру́скїй ѧзы́къ (ruskiy yazyk').
• Prosta(ja) mova (meaning: the simple speech, or the simple talk), also written in various ways, as: прост(ѧ) мова or простй ѧзыкъ (Old Belarusian / Old Ukrainian: простый руский (язык) or простая молва, проста мова) – publisher Hryhorii Khodkevych (16th century). Those terms for simple vernacular speech were designating its diglossic opposition to literary Church Slavonic.^[12][13][14]
• It was sometimes also referred to (in territorial terms) as Litovsky (Russian: Литовский язык / Lithuanian). Also by Zizaniy (end of the 16th century), Pamva Berynda (1653).

Common exonyms:

• in Latin: lingua ruthenica, or lingua ruthena, which is rendered in English as: Ruthenian or Ruthene language.^[15]
• in German: ruthenische Sprache, derived from the Latin exonym for this language.
• in Hungarian: Rutén nyelv, also derived from the Latin exonym.

Modern names of this language and its varieties, that are used by scholars (mainly linguists), can also be divided in two basic categories, the first including those that are derived from endonymic (native) names, and the second encompassing those that are derived from exonymic (foreign) names.

Names derived from endonymic terms:

• One "s" terms: Rus’ian, Rusian, Rusky or Ruski, employed explicitly with only one letter "s" in order to distinguish this name from terms that are designating modern Russian.^[16]
• West Russian language or dialect (Russian: западнорусский язык, западнорусское наречие)^[17] – terms used mainly by supporters of the concept of the Proto-Russian phase, especially since the end of the 19th century. Employed by authors such as Karskiy and Shakhmatov.^[18]
• Old Belarusian language (Belarusian: Старабеларуская мова) – term used by various Belarusian and some Russian scholars, and also by Kryzhanich. The denotation Belarusian (language) (Russian: белорусский (язык)) when referring both to the post-19th-century language and to the older language had been used in works of the 19th-century Russian researchers Fyodor Buslayev, Ogonovskiy, Zhitetskiy, Sobolevskiy, Nedeshev, Vladimirov and Belarusian researchers, such as Karskiy.^[19]
• Old Ukrainian language (Ukrainian: Староукраїнська мова) – term used by various Ukrainian and some other scholars.
• Lithuanian-Russian language (Russian: литовско-русский язык) – regionally oriented designation, used by some 19th-century Russian researchers such as: Keppen, archbishop Filaret, Sakharov, Karatayev.
• Lithuanian-Slavic language (Russian: литово-славянский язык) – another regionally oriented designation, used by 19th-century Russian researcher Baranovskiy.^[20]
• Chancery Slavonic, or Chancery Slavic – a term used for the written form, based on Old Church Slavonic, but influenced by various local dialects and used in the chancery of Grand Duchy of Lithuania.^[13][21]

Names derived from exonymic terms:

• Ruthenian or Ruthene language – modern scholarly terms, derived from older Latin exonyms (Latin: lingua ruthenica, lingua ruthena), commonly used by scholars who are writing in English and other western languages, and also by various Lithuanian and Polish scholars.^[22][23]
• Ruthenian literary language, or Literary Ruthenian language – terms used by the same groups of scholars in order to designate more precisely the literary variety of this language.^[7]
• Ruthenian chancery language, or Chancery Ruthenian language – terms used by the same groups of scholars in order to designate more precisely the chancery variety of this language, used in official and legal documents of the Grand Duchy of Lithuania.^[24]
• Ruthenian common language, or Common Ruthenian language – terms used by the same groups of scholars in order to designate more precisely the vernacular variety of this language.^[25]
• North Ruthenian dialect or language – a term used by some scholars as designation for northern varieties, that gave rise to modern Belarusian language,^[26] that is also designated as White Ruthenian.^[27]
• South Ruthenian dialect or language – a term used by some scholars as designation for southern varieties, that gave rise to modern Ukrainian language,^[28][29] that is also designated as Red Ruthenian.

Terminological dichotomy, embodied in parallel uses of various endoymic and exonymic terms, resulted in a vast variety of ambiguous, overlapping or even contrary meanings, that were applied to particular terms by different scholars. That complex situation is addressed by most English and other western scholars by preferring the exonymic Ruthenian designations.^[30][31][23]

Daniel Bunčić suggested a periodization of the literary language into:^[32]

1. Early Ruthenian, dating from the separation of Lithuanian and Muscovite chancery languages (15th century) to the early 16th century
2. High Ruthenian, from Francysk Skaryna (fl. 1517–25), to Ivan Uzhevych (Hramatyka slovenskaia, 1643, 1645)
3. Late Ruthenian, from 1648 to the establishment of the Ukrainian and Belarusian standard languages at the end of the 18th century

According to linguist Andrii Danylenko (2006), what is now called 'Ruthenian' first arose as a primarily administrative language in the 14th and 15th centuries, shaped by the chancery of the Grand Duchy of Lithuania in Vilnius (Vilna).^[33][a] He identified the Polissian (Polesian) dialect spoken on both sides of the modern Belarusian–Ukrainian border as the basis of both written Ruthenian (rusьkij jazykъ or Chancery Slavonic) and spoken dialects of Ruthenian (проста(я) мова prosta(ja) mova or "simple speech"),^[34] which he called 'two stylistically differentiated varieties of one secular vernacular standard'.^[35]

From the second half of the 15th century through the 16th century, when present-day Ukraine and Belarus were part of the Grand Duchy of Lithuania, the Renaissance had a major impact on shifting culture, art and literature away from Byzantine Christian theocentrism as expressed in Church Slavonic.^[36] Instead, they moved towards humanist anthropocentrism, which in writing was increasingly expressed by taking the vernacular language of the common people as the basis of texts.^[36] New literary genres developed that were closer to secular topics, such as poetry, polemical literature, and scientific literature, while Church Slavonic works of previous times were translated into what became known as Ruthenian, Chancery Slavonic, or Old Ukrainian (also called проста мова prosta mova or "simple language" since the 14th century).^[37] It is virtually impossible to differentiate Ruthenian texts into "Ukrainian" and "Belarusian" subgroups until the 16th century; with some variety, these were all functionally one language between the 14th and 16th century.^[38]

The vernacular Ruthenian "business speech" (Ukrainian: ділове мовлення, romanized: dilove movlennya) of the 16th century would spread to most other domains of everyday communication in the 17th century, with an influx of words, expressions and style from Polish and other European languages, while the usage of Church Slavonic became more restricted to the affairs of religion, the church, hagiography, and some forms of art and science.^[39]

The 1569 Union of Lublin establishing the Polish–Lithuanian Commonwealth had significant linguistic implications: the Crown of the Kingdom of Poland (which now included Ukraine) had previously used Latin for administration, but switched to Middle Polish (standardised c. 1569–1648^[40]), while the Grand Duchy of Lithuania (including Belarus, but no longer Ukraine) gave up Chancery Slavonic (Ruthenian) and also switched to Middle Polish.^[40] Much of the Polish and Ruthenian nobility briefly converted to various kinds of Protestantism during the Reformation, but in the end all of them either returned or converted to Catholicism and increasingly used the Polish language; while Ukrainian nobles thus Polonised, most Ukrainian (and Belarusian) peasants remained Orthodox-believing and Ruthenian-speaking.^[41]

When the Cossack Hetmanate arose in the mid-17th century, Polish remained a language of administration in the Hetmanate, and most Cossack officers and Polish nobles (two groups which overlapped a lot) still communicated with each other using a combination of Latin, Polish and Ruthenian (Old Ukrainian).^[42] On the other hand, the language barrier between Cossack officers and Muscovite officials had become so great that they needed translators to understand each other during negotiations, and hetman Bohdan Khmelnytsky 'had letters in Muscovite dialect translated into Latin, so that he could read them.'^[42]

The 17th century witnessed the standardisation of the Ruthenian language that would later split into modern Ukrainian and Belarusian.^[43] From the 16th century onwards, two regional variations of spoken Ruthenian began to emerge as written Ruthenian gradually lost its prestige to Polish in administration.^[38] The spoken prosta(ja) mova disappeared in the early 18th century, to be replaced by a more Polonised (central) early Belarusian variety and a more Slavonicised (southwestern) early Ukrainian variety.^[38] Meanwhile, Church Slavonic remained the literary and administrative standard in Russia until the late 18th century.^[44]

• Church Slavonic in Romania
• Linguonym
• Slavic studies
• Galicia (Eastern Europe)
• Ruthenian Uniate Church

• "Hrodna town books language problems in Early Modern Times" by Jury Hardziejeŭ
• Zinkevičius, Zigmas. "Lietuvos Didžiosios Kunigaikštystės kanceliarinės slavų kalbos termino nusakymo problema". viduramziu.istorija.net (in Lithuanian). Archived from the original on 10 July 2009. Retrieved 2 August 2018.