Semelfactives in -nu- | Serbian Grammar

Serbian often uses -ну- to create a perfective verb meaning one bounded occurrence of an activity: капати : капнути “drip : drip once,” трептати : трепнути “blink repeatedly : blink once,” and махати : махнути “wave : make one wave.” Such one-act verbs are called semelfactives, a particularly clear instance of the event boundary explained on the perfective meaning page.

The pattern is useful, but it is not a mechanical rule for every word ending in -нути. Some verbs with that spelling are not semelfactive, and some one-act meanings use other morphology. Learn the lexical network, its principal forms, and the kind of event each member names.

One act versus an activity or series

An imperfective base presents an activity internally or as repeated occurrences. Its semelfactive relative extracts one bounded token from that activity.

Activity / repeated acts	One bounded act	Practical contrast
капати	капнути	drip / release one drop
трептати	трепнути	blink repeatedly / blink once
махати	махнути	wave / make one wave
куцати	куцнути	knock or tap / make one knock or tap
гурати	гурнути	push as an activity / give one push
викати	викнути	shout repeatedly or continuously / utter one shout

Славина је капала целе ноћи, а сада само повремено капне.

The tap dripped all night, and now it only releases a drop occasionally.

Капала opens a continuing series. Perfective капне isolates each occurrence, while повремено places those bounded tokens in a repeated frame. Perfective therefore does not mean “past”: капне is morphologically present and has a habitual-distributive interpretation here.

Дете је трептало због јаког светла, а онда је једном споро трепнуло.

The child kept blinking because of the bright light, then blinked slowly once.

The adverb једном makes the one-act reading explicit. Споро shows an important point: a semelfactive is one bounded act, but the act need not be literally instantaneous.

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“One act” is safer than “instantaneous.” A wave, push, or step can have perceptible duration and still be construed as one indivisible occurrence.

Semelfactives are perfective, not past-tense forms

The -ну- derivative supplies a bounded event; tense and mood are added separately. It can occur in the past, future, imperative, or a future-oriented subordinate clause.

Махнула ми је кроз прозор аутобуса и нестала из вида.

She waved to me once through the bus window and disappeared from view.

Кад ти махнем, отвори задња врата.

When I wave to you, open the back door.

Куцни два пута ако су улазна врата закључана.

Knock twice if the entrance door is locked.

Perfective present махнем refers to a prospective boundary after кад. Imperative куцни requests bounded knocks; два пута counts two one-act events. The repetition happens outside each semelfactive token rather than changing its aspect.

Compare an ongoing request:

Куцај јаче док ти не отворе.

Keep knocking more loudly until they open the door for you.

Imperfective куцај requests continued or repeated knocking. A single куцни would not match that persistence.

Principal forms must be learned

The infinitive does not reveal every stem alternation. For productive one-act verbs, the present commonly has -нем, and the imperative has -ни.

Infinitive	1st singular / 3rd plural present	L-participle	2nd singular imperative
трепнути	трепнем / трепну	трепнуо, трепнула	трепни
махнути	махнем / махну	махнуо, махнула	махни
куцнути	куцнем / куцну	куцнуо, куцнула	куцни
гурнути	гурнем / гурну	гурнуо, гурнула	гурни

Само сам благо гурнуо врата и она су се сама отворила.

I only gave the door a gentle push, and it opened by itself.

The masculine l-participle гурнуо retains -ну-. Agreement changes the ending: гурнула је, гурнули су. Object врата is plural in Serbian, hence она су се отворила.

Some -нути verbs show less transparent l-participles, including competing short and long forms, and must be learned with their principal forms.

Infinitive	Present	Masculine / feminine l-participle	Imperative
пукнути	пукнем	пукао / пукла (neutral baseline); пукнуо / пукнула also occurs	пукни
дигнути	дигнем	дигао / дигла; also дигнуо / дигнула	дигни

Грана је пукла под тежином мокрог снега.

The branch snapped under the weight of the wet snow.

The shorter forms are a safe neutral baseline. Longer forms with -ну- also occur in contemporary usage—Serbian morphological descriptions explicitly document дигнуо beside дигао—so retained -ну- should not automatically be “corrected.” Preferences differ by lexeme and speaker.

Not every -нути verb is semelfactive

The visible sequence -нути can belong to a different morphological history or lexical class. Бринути “worry/care,” гинути “perish,” тонути “sink,” and венути “wither” are imperfective; they do not mean one instance of брити, гити, or similar nonexistent bases.

Бринем за њу, али не желим да је стално зовем.

I worry about her, but I do not want to call her constantly.

Present бринем describes an ongoing state. The ending of the infinitive is not a license to label it semelfactive or perfective.

Other -нути verbs are perfective but express an onset, achievement, or change rather than one token extracted from a repeated activity. Кренути means “set off/start moving,” and погинути means “be killed/lose one's life.” Their boundedness is real, but calling them “one instance of an imperfective action” would hide their lexical meanings.

Аутобус је кренуо чим су се врата затворила.

The bus set off as soon as the doors closed.

There is no general imperfective кретати that is simply “do many set-offs” in every context; кретати and кренути form a network with onset and motion meanings that must be learned lexically.

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First determine whether -ну- is the productive one-act suffix in this particular verb. The spelling -нути alone does not establish either semelfactivity or even perfective aspect.

Repetition can count semelfactive tokens

A semelfactive remains perfective when a quantifier counts several acts.

Три пута је трепнула, па се поново загледала у екран.

She blinked three times, then stared at the screen again.

This sentence contains three complete blink events. For uncounted rapid repetition, imperfective is more natural:

Трептала је неколико секунди док јој се вид није разбистрио.

She kept blinking for several seconds until her vision cleared.

The same lexical situation therefore supports either member. Count bounded tokens with трепнути; profile the repeated activity with трептати.

A short dialogue

— Јеси ли куцао? — Јесам, дуго сам куцао, а онда сам једном куцнуо по стаклу.

— Did you knock? — Yes, I knocked for a long time, and then I tapped the glass once.

The question asks generally about knocking activity. The reply contrasts that activity with one final bounded tap. Replacing куцнуо with куцао after једном would lose the deliberately isolated one-act reading.

Common Mistakes

Treating every infinitive in -нути as semelfactive

❌ „Бринути“ значи „забринути се једном“ зато што се завршава на -нути.

Incorrect — ‘бринути’ is an imperfective state verb; the letters -нути do not automatically form a semelfactive.

✅ Бринем због резултата, али покушавам да останем миран.

I am worried about the results, but I am trying to stay calm.

Using a one-act verb for sustained activity

❌ Махнуо је заставом пет минута, па је стао.

Incorrect for sustained waving — the semelfactive ‘махнуо’ denotes one wave, while a five-minute activity requires ‘махао’.

✅ Махао је заставом пет минута, па је стао.

He waved a flag for five minutes, then stopped.

Building the l-participle from the imperative

❌ Кабл је пукнио током олује.

Incorrect — ‘пукни’ is the imperative, not the stem of the l-participle; use neutral ‘пукао’, while the distinct longer form ‘пукнуо’ also occurs.

✅ Кабл је пукао током олује.

The cable snapped during the storm.

Equating perfective with past

❌ Облик „трепнем“ не може да се односи на будућност јер је свршен.

Incorrect — aspect marks a bounded act, while the subordinate clause supplies future orientation.

✅ Чим трепнем, промени слајд.

As soon as I blink, change the slide.

Practice

Task 1: Choose one act or an activity

Complete four short contexts with the appropriate member: капати / капнути, махати / махнути, куцати / куцнути, трептати / трепнути. Use a bare duration in two contexts and једном or три пута in the other two. Explain what is being counted.

Task 2: Learn principal forms

Give the first-person present, feminine l-participle, and second-person singular imperative of гурнути, пукнути, and махнути. Then identify which verb has common short and long l-participle doublets.

Key Takeaways

Productive semelfactive -ну- extracts one bounded act from an activity or repeated series.
One-act does not necessarily mean physically instantaneous, and counted semelfactive tokens can be repeated.
The spelling -нути does not guarantee a semelfactive or even a perfective verb.
Learn principal forms because verbs such as пукнути have nontransparent and sometimes competing l-participles.

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