What grammatical features do most Slavic languages share?

Slavic languages are a close-knit group that share several distinct grammatical characteristics rooted in their Proto-Slavic origins.

Core Grammatical Features

• Synthetic Structure: All Slavic languages are synthetic, primarily expressing grammatical meaning through inflection—using endings, prefixes, and vowel or consonant alternations.1
• Noun Declension: Most Slavic languages retain a system of seven cases (nominative, genitive, dative, accusative, locative, instrumental, and vocative), though Bulgarian and Macedonian have largely replaced this with analytical constructions using prepositions.2
• Gender and Animacy: Nouns are categorized into three genders: masculine, feminine, and neuter. Most languages further distinguish between animate and inanimate masculine forms.3
• Verb Aspect: A defining feature is the overt use of verb aspect, where verbs typically exist in pairs to distinguish between perfective (completed) and imperfective (uncompleted) actions.14
• Auxiliary Usage: Slavic auxiliary words are generally unstressed and incorporated into a single phonetic phrase with an autonomous stressed word.1

While these languages share a common foundation, they exhibit varying degrees of drift toward analytical structures, particularly in the South Slavic branch.124