-а (генитив множине)

In Serbian, the genitive plural is used after adverbs of quantity (много, мало, неколико), cardinal numerals 5 and above (пет и више, including 5–20, 30, 50, 100, etc.), compound numerals where agreement is governed by the final word whenever it is a single digit from 5 to 9, a teen number from 11 to 19, or a round ten or hundred ending in zero (e.g., двадесет пет, сто дванаест, сто педесет; see compound number agreement), and many prepositions.

How -а Attaches by Gender:

• Masculine nouns: Regular multi-syllable nouns add -а to the stem (прозор → прозора). In native nouns with fleeting а, the vowel that disappeared in the singular oblique cases reappears in the genitive plural (момак → момка → момака; пас → пса → паса). Polysyllabic loanwords ending in clusters like -нт or -рт regularly split epenthetically with fleeting а (студент → студената, асистент → асистената, концерт → концерата). Conversely, loanword stems ending in clusters like -нг or -кс add -а directly without splitting (митинг → митинга, рефлекс → рефлекса). Monosyllabic loanwords ending in consonant clusters typically take the extended stem with -ов- / -ев- (спорт → спортова, старт → стартова). Most short masculine nouns take the extended stem -ов- / -ев- before adding -а (град → градова, кључ → кључева), though some frequent monosyllabic nouns form a short plural without this infix and add -а directly to the root (зуб → зуба, дан → дана, коњ → коња). Additionally, masculine nouns ending in -а (such as судија, колега) follow the feminine -а declension and also take -а in the genitive plural (пет судија, много колега).
• Feminine nouns ending in -а: Simple stems add -а (жена → жена). In certain stems ending in consonant clusters, an epenthetic fleeting а splits the consonants (e.g., оловка → оловака, сестра → сестара, земља → земаља). While nouns ending in the cluster -јк- standardly take the ending -и (мајка → мајки), девојка takes fleeting а (девојака), and words like бајка permit doublets (бајки / бајака). Other stems with clusters in -ск-, -зк-, -цк-, or feminine agent nouns and ethnonyms in -ка also take -и instead of fleeting а (e.g., војска → војски, маска → маски, лекарка → лекарки, Босанка → Босанки). Stems containing clusters with sibilants followed by stops or affricates (ст, зд, шт, шћ) add -а directly without vowel insertion (e.g., врста → врста, башта → башта). Many other feminine nouns with clusters take -и or doublet forms with stem lengthening (молба → молби / мо̄лба̄, лопта → лопти / ло̄пта̄).
• Neuter nouns: Most neuter nouns replace -о or -е with -а (село → села). Stems ending in consonant clusters generally insert a fleeting а (писмо → писама), though clusters with ст, зд, шт, шћ do not insert it (место → места, позориште → позоришта). Neuter nouns with an extended stem in -ен- (именице на -ме; -те) attach -а to the extended base (име → имена, време → времена).

Disambiguation (The Genitive Sign):
Because feminine nominative singular (жена), neuter nominative plural (села), and masculine genitive singular (прозора) also end in -а, spoken Serbian distinguishes the genitive plural by its distinctive long vowel -а̄ and characteristic pitch/accent patterns. In written texts where the grammatical context could be ambiguous, a circumflex (генитивни знак, ^) is often placed over the vowel (e.g., жена̂).