The Fleeting 'a' (nepostojano a) | Serbian Grammar

The fleeting а (непостојано а) is a vowel that belongs to one shape of a stem but disappears from another: момак — момка, пас — пса, добар — добра. It can also appear where the citation form has no а, especially in genitive plural: сестра — сестара, писмо — писама.

This is not an optional pronunciation shortcut. The presence or absence of а is part of the standard inflected form. Case and number select a stem shape; Serbian spelling then records that shape exactly.

One noun can have two stem shapes

For many masculine nouns, the nominative singular contains а between the last two consonants. Before most vowel-initial endings, that а disappears.

Case	Singular of пас	Plural of пас
Nominative	пас	пси
Genitive	пса	паса
Dative	псу	псима
Accusative	пса	псе
Vocative	псе	пси
Instrumental	псом	псима
Locative	псу	псима

The pattern is revealing. А appears in nominative singular пас and returns in genitive plural паса, but the cluster пс- appears through the rest of the paradigm. The animate accusative singular is пса, identical to the genitive singular; the vowel alternation does not cancel masculine animacy.

Пас је заспао испод стола док смо вечерали.

The dog fell asleep under the table while we were having dinner.

Сваког јутра водим пса до оближњег парка.

Every morning I take the dog to the nearby park.

Ветеринар је данас прегледао шест паса из азила.

The veterinarian examined six dogs from the shelter today.

The same two-stem behavior appears in момак — момка — момака, писац — писца — писаца, ветар — ветра, пројекат — пројекта — пројеката, and сан — сна — снова. The plural is not uniform across all of them, so learn a small diagnostic set rather than a mechanical recipe.

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Record a new masculine noun with its genitive singular and genitive plural: пројекат — пројекта — пројеката. Those three forms reveal the fleeting vowel and one of the least predictable plural cells.

It is not “delete any a before an ending”

Compare момак — момка with јунак — јунака. Both nominatives end in -ак, but the first а is fleeting and the second is stable. Similarly, дан — дана keeps its vowel, while сан — сна loses it.

Nominative	Genitive singular	Behavior
момак	момка	а disappears
пројекат	пројекта	а disappears
јунак	јунака	а remains
дан	дана	а remains
сан	сна	а disappears

Historically, the alternation reflects an old reduced vowel, but the modern distribution is lexical and morphological. Consonant clusters offer a clue, not a complete prediction: Serbian accepts пс-, сн-, and ветр- in inflected forms, while other words keep а. There is no honest shortcut that predicts every noun from nominative alone.

После напорног дана потребан ми је миран сан.

After a demanding day, I need a peaceful night’s sleep.

Из сна ме је пренуо звук првог аларма.

The sound of the first alarm startled me awake.

Here дана keeps its stem vowel, whereas сна uses the reduced stem. Both are genitives, so “genitive deletes а” is not the rule.

Adjectives and determiners alternate too

The fleeting vowel is not confined to nouns. It appears in masculine nominative singular forms of many adjectives and determiners, then disappears elsewhere:

Masculine nominative	Feminine nominative	Neuter nominative	Masculine genitive
добар	добра	добро	доброг
кратак	кратка	кратко	кратког
снажан	снажна	снажно	снажног
један	једна	једно	једног
какав	каква	какво	каквог

Case agreement can make two fleeting vowels disappear within one phrase:

Један добар момак нам је помогао да унесемо орман.

A nice young man helped us carry the wardrobe inside.

Захвалили смо једном добром момку на помоћи.

We thanked a nice young man for his help.

The nominative phrase has један добар момак; dative једном добром момку loses а in all three words. Each word follows its own paradigm, but phrase-wide gender, number, and case choose compatible forms.

Another sound change can accompany the loss. In сладак — слатког, the fleeting а disappears and д is devoiced to т before к. In момак — момци, vowel loss and к → ц occur together. Do not call every difference “fleeting а”; separate the vowel alternation from consonant alternations in declension.

The reverse pattern in genitive plural

Genitive plural frequently brings а into a consonant cluster. This happens in feminine -а nouns and many neuter nouns:

Nominative singular	Nominative plural	Genitive plural
сестра	сестре	сестара
девојка	девојке	девојака
земља	земље	земаља
тачка	тачке	тачака
писмо	писма	писама
ребро	ребра	ребара

На изложби су представљени радови дванаест девојака из шест земаља.

The exhibition featured works by twelve girls from six countries.

У фиоци сам пронашла гомилу старих писама и разгледница.

I found a pile of old letters and postcards in the drawer.

The quantity words select genitive plural, but the plural form must still be learned noun by noun. Пет сестара has inserted а, while пет жена and пет књига do not. A difficult cluster often motivates insertion, yet it does not license learners to insert a vowel wherever they find a cluster inconvenient.

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The two useful directions are “disappears in an oblique stem” (момак → момка) and “appears in genitive plural” (сестра → сестара). Calling both patterns fleeting а prevents the false idea that it always starts in the nominative.

Case, number, and meaning still come first

The vowel never chooses the case. A verb, preposition, quantity, or semantic role chooses the case; the paradigm then supplies the correct stem.

Разговарам с младим писцем, али још нисам прочитао ниједан његов роман.

I’m talking with a young writer, but I still haven’t read any of his novels.

Уредница је позвала пет младих писаца на округли сто.

The editor invited five young writers to the roundtable.

С писцем is instrumental singular and has no а. After пет, писаца is genitive plural and restores it. English “writer/writers” gives no warning that Serbian uses two stem shapes here.

For pure spelling and script-conversion practice, see the fleeting a in spelling. In declension, your aim is to connect each shape to a full case-number cell.

Practice Tasks

Task 1: Build the case set

Put овај добар момак into genitive singular after без, dative singular after помоћи, and genitive plural after пет.

Без овог доброг момка не бисмо завршили; помогли смо овом добром момку; позвали смо пет добрих момака.

Without this nice young man we wouldn’t have finished; we helped this nice young man; we invited five nice young men.

Task 2: Decide whether а is stable

Compare the requested genitives of дан, сан, јунак, and пројекат.

После дугог дана разговарали смо о значењу сна, успеху јунака и року пројекта.

After a long day, we talked about the meaning of the dream, the hero’s success, and the project deadline.

The forms дана and јунака keep а; сна and пројекта lose it.

Common Mistakes

Keeping the nominative vowel in an oblique singular

❌ Не могу да пронађем број тог пројеката.

Incorrect — пројеката is genitive plural; genitive singular is пројекта.

✅ Не могу да пронађем број тог пројекта.

I can’t find that project’s number.

Deleting every internal а

❌ После напорног дна одмах сам заспао.

Incorrect — дан keeps а in genitive singular: дана; the vowel is not fleeting in this noun.

✅ После напорног дана одмах сам заспао.

After a demanding day, I fell asleep immediately.

Failing to decline the modifier with the noun

❌ Захвалили смо добар момку на искреном савету.

Incorrect — dative agreement requires добром, and момак has dative момку.

✅ Захвалили смо добром момку на искреном савету.

We thanked the nice young man for his honest advice.

Using a singular-looking form after a higher number

❌ У жирију је било седам познатих писца.

Incorrect — седам requires genitive plural писаца, with а restored.

✅ У жирију је било седам познатих писаца.

There were seven well-known writers on the jury.

Key Takeaways

Learn alternating stems as sets: момак — момка — момака, пас — пса — паса.
The pattern is lexical: сан — сна, but дан — дана.
Modifiers have their own fleeting vowel: један добар момак — једног доброг момка.
Genitive plural can introduce а: сестара, девојака, земаља, писама.
Case and number choose the form; the vowel alternation does not determine the syntax.

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