[1] The four languages are descended from a common ancestor developed from the Vulgar Latin spoken in southeastern Europe during Classical Antiquity.
[5] Studies of the South Slavic languages revealed that Bulgarian and Serbian developed for centuries in two distant territories, separated by significant non-Slavic groups.
[8] In contrast, linguist Gottfried Schramm proposes that the Romanians' ancestors lived in the mountains, surrounded by Albanian-speaking communities and thus separated from the Slavs of the lowlands until the 10th century.
[10] Contacts with Slavic-speaking groups intensified before the disintegration of Common Romanian and about 80 Slavic loanwords are still present in all four Eastern Romance variants.
[16] They developed a Latin-based alphabet to replace the Cyrillic writing system and promoted the use of Latin terms in place of words of Slavic origin.
[16] Wallachian writers started to advance the adoption of loanwords from Romance languages (especially from French and Italian) in the 19th century.
[23][24] Studies determined that about 16.5% of the nouns, 14% of the verbs (most of which have the fourth conjugation form), 11.8% of the adjectives, 20% of the adverbs and 1.6% of the function words were borrowed from Slavic languages.
[24] The ratio of Slavic loanwords is especially high in the religious vocabulary (25%) and in the semantic field of social and political relations (22.5%).
[25] Slavic loanwords make up more than 10% of the Romanian terms related to speech and language, to basic actions and technology, to time, to the physical world, to possession and to motion.
[29] In some cases, certain dialects retained inherited Latin term which were replaced by Slavic loanwords in standard Romanian.
[26] For example, the inherited Latin term for snow (nea) is only used regionally or in poems, while standard Romanian prefers zăpadă and omăt which were borrowed from Slavic languages.
[26] Most Slavic loanwords are connected to situations which stir up emotions, including dragă ("dear") and slab ("weak").
[35] For instance, the Latin word for life (vita) developed into the Romanian term for cattle (vită) following the pattern of Old Church Slavonic životŭ ("being" and "animal").
[39] The structure of the Romanian decades above ten follows a digit-decad system: douăzeci ("two-tens" for 20), treizeci ("three-tens" for 30) and patruzeci ("four-tens" for 40).
[46] Most Slavic consonant clusters with a first fricative were fully adopted: vlădică ("bishop" from vladika), slugă ("servant" from sluga), zmeu ("dragon" from zmey).
[49] The word-initial "zdr"-cluster appears both in Slavic loanwords, like zdravăn ("strong") and a zdrobi ("to crush"), and in words of unknown origin, like a zdruncina ("to shake") and a zdrăngăni ("to tinkle").
[51] Pre-ioticization can only be detected in eight forms of the verb a fi ("to be") and in four personal pronouns, but three archaic demonstratives also displayed this phonetic change.
[52] Palatalization of consonants before the vowel "i" is also attributed to Slavic influence by a number of scholars, but others maintain that it developed internally.
[64] Romanian is the sole major Romance language still using the vocative case when addressing a person: domnule ("sir!
[72] Linguists Jacques Byck and Ion Diaconescu maintain that the infinitive shortened without external influence during the development of Romanian.
[79] Petrucci and other linguists studying the grammatical gender in Romanian in recent years generally agree[80] that it is the result of an internal historical development.
[81][82][83][84] A couple of words inherited from Latin used in active voice in other Romance languages became reflexive in Romanian under a Slavic influence.