Conjugation (Infinitive stems and present tense stem   •   Present   •   Past   •   Future   •   Conditional   •   Imperative   •   Participles, gerund   •   Passive voice)
Irregular verbs (Byti   •   Dati, jesti, věděti   •   Idti)

Perfective and imperfective aspect (Sovršeny i nesovršeny vid)

One of the greatest nightmares of people learning a Slavic languages are verbs, which are characterized by many different conjugations, exceptions and exceptions on exceptions. Perhaps the hardest thing for non-Slavs to get used to is lexical aspect: most verbs exist in two different forms („aspects”), perfective and imperfective. Most perfective verbs have an imperfective counterpart and vice versa. Usually, they need to be learned separately. Complicated as this may be for foreigners, it is a very characterstic feature of Slavic, omnipresent in all Slavic languages, and therefore cannot be avoided in Interslavic. All we can do is make the system as transparent and regular as possible. Still, both forms, perfective and imperfective, are listed separetely in the dictionary.

In short, perfective aspect focuses on the result of an action and not on the action itself. Depending on tense, it means that the action has been completed already or will be completed at some point. Imperfective aspect, on the other hand, focuses on action itself; it indicates that on the point of reference the action is or was going on. It can also express a an ongoing process, a habit or a repeated action: ja čital jesm knigu (imperfective) means „I was reading a book” or „I have been reading a book”, ja pročital jesm knigu (perfective) means „I have read a book (and finished it)”.

Verbs without a prefix are imperfective almost by definition. Most imperfective verbs have a perfective equivalent that means exactly the same thing, except that it focuses on the result of the action. In general, this perfective version is formed by adding a prefix:
dělati (impf.) > sdělati (pf.) „to do”
čistiti (impf.) > izčistiti (pf.) „to clean”
pisati (impf.) > napisati (pf.) „to write”

In general, however, the purpose of placing a prefix in front of a verb is to modify its meaning. Whereas in the case of pisati the prefix na- simply turns it into a perfective verb, other prefixes can be used as well, for example za- in zapisati „to record, to register” or pod- in podpisati „to sign, to subscribe”. Because the resulting verb is always perfective, a „secondary” imperfective verb is needed that is based on its perfective equivalent. These imperfective verbs are formed as follows:

Sometimes aspect pairs are irregular, for example nazyvati (impf.)/nazvati (pf.) „to call, to name”, prihoditi (impf.)/prijdti (pf.) „to come”, podimati (impf.)/podjeti (pf.) „to take up, to undertake”.

A special category of verbs in terms of aspects are verbs of motion. Unlike other verbs, they usually make a three-way distinction: non-directional imperfective, directional imperfective, perfective. The first of these expresses movement without any particular direction, and therefore has no perfective equivalent of its own. For example:

non-directional directional impf. perfective
to go (by foot) hoditi idti pojdti
to by (by transport) jezditi jehati pojehati
to fly lětati letiti poletiti
to run běgati běgti poběgti
to climb laziti lězti polězti
to crawl polzati polzti popolzti
to swim plavati plyvti poplyvti
to sail plavati pluti popluti
to fall padati pasti upasti
to carry nositi nesti ponesti
to transport voziti vezti povezti
to lead voditi vesti povesti

For example: Igor jezdil po Moskvě „Igor was driving around in Moscow”. Igor jehal do Moskvy „Igor was driving do Moscow”. Igor pojehal do Moskvy „Igor has gone to Moscow”.

When a non-directional verb of motion has a direction anyway, this expresses a habit: Igor jezdil do Moskvy „Igor [always|often] went to Moskow”.

Except for hoditi, idti and pojdti, there is also the word pohoditi, which can express „to walk a bit”, but also „to walk in multiple directions”.

In compounds with a prefix, the non-directional form is used for the imperfective verb, the directional form for thee perfective verb:
odhoditi (impf.)/oditi (pf.) „to go away”
dolětati (impf.)/doletiti (pf.) „to arrive (by flight)”
prinositi (impf.)/prinesti (pf.) „to bring”

Conjugation (Časovanje)

Aspect is one thing that might take a while getting used to, conjugation is another. The Slavic languages are characterised by a large number of different conjugations, combinations of conjugations („classes”), exceptions and irregular verbs. In addition to this, the Slavic languages have a varying number of moods and tenses, and three languages (Slovene, Upper and Lower Sorbian) also have separate forms for the dual. Verbal conjugation in Interslavic has been simplified to the highest possible extent, while still preserving naturalism and without resorting to artificial solutions. As a result:

Infinitive stem and present tense stem

In the dictionary, verbs are always given in the infinitive. All infinitives have the ending -ti: dělati „do, make”, uměti „can, to be able”, prositi „to ask”, nesti „to carry”, pisati „to write”, čuti „to feel”, kovati „to forge”, tegnuti „to pull”. Usually, knowing the infinitive is enough for knowing the entire conjugation of a verb.

The infinitive stem is created by removing the ending -ti, and serves as a starting point for the past tenses, the conditional, the past participles and the verbal noun.

Infinitives are almost always regular, so that the ending -ti does not alter the infinitive stem. This is also the case in verbs like mogti „can”, pekti „to bake”, běgti „to run” etc. (instead of the expected but less transparant moči, peči and běči). The only exceptions are verbs on -sti: in most cases, their infinitive stems end in d, sometimes also t or s. For example klasti „to lay, to put”, pasti „to fall” and gnesti „to crush” have the stems klad-, pad- and gnet-. To distinguish these cases from nesti (stem: nes-) and the like, they are represented in the dictionary as follows: klasti (klad-e), gnesti (gnet-e).

Usually, the present tense stem (used for the present tense, the imperative and the present participles) can be derived regularly from the infinitive stem. There is a difference between the first and the second conjugation:

A number of verbs use a separate root in the present tense. In most cases, these are verbs of the mixed a/j, a/i and ě/i classes in Slavic. An active user of Interslavic will have to learn both forms. He will notice, however, that in most cases the formation of this second root happens in a predictable way. Whenever the present-tense stem cannot be derived from the infinitive by applying the rules above, it will be given in the dictionary. A few examples: pisati (piš-e) „to write”, htěti (hoč-e) „to want”, spati (sp-i) „to sleep”, zvati (zov-e) „to call”, brati (ber-e) „to take (impf.)”, vzeti (vozm-e) „to take (pf.)”.

Present tense

In the present tense, the endings for the two conjugations are the following:

Instead of -u/-ju in the first person singular, -em/-im can be used as well: nesem, hvalim. The former are characteristic especially for East Slavic and Polish, the latter for Slovak and South Slavic.

The West and South Slavic languages also have a third conjugation, based on contraction of -aje- sequences, resulting in the endings: -am, -aš, -a, -amo, -ate, -ajut.


First conjugation Second conjugation
infinitive dělati nesti hvaliti viděti
present-tense stem dělaj- / děl- nes- hval-i- vid-i-
ja dělaju / dělam nesu / nesem hvalju / hvalim vidžu / vidim
ty dělaješ / dělaš neseš hvališ vidiš
on/ona/ono dělaje / děla nese hvali vidi
my dělajemo / dělamo nesemo hvalimo vidimo
vy dělajete / dělate nesete hvalite vidite
oni/one dělajut nesut hvalet videt


Past tense

Basically, there are two different methods for dealing with the past tense. Most commonly used is the compound past, made by combining the present tense of the verb byti „to be” with the so-called L-participle. This participle carries a meaning similar to „being in a state of having done something”, and is formed by adding the ending -l (masculine singular), -la (feminine singular), -lo (neuter singular) or -li (universal plural) to the infinitive stem.

In the third person, the forms of byti (je, jest, sut) are usually omitted, although this is not mandatory.

This system gives an imperfect tense when applied to imperfective verbs (ja jesm dělal „I did, I was doing”), and a perfect tense when applied to perfective verbs (ja jesm sdělal „I have done”).


infinitive dělati nesti hvaliti
infinitive stem děla- nes- hvali-
ja jesm dělal(a) jesm nesl(a) jesm hvalil(a)
ty jesi dělal(a) jesi nesl(a) jesi hvalil(a)
my jesmo dělali jesmo nesli jesmo hvalili
vy jeste dělali jeste nesli jeste hvalili
oni/one dělali nesli hvalili

The L-participle is always formed regularly except for one verb: idti „to go” has šel, šla, šlo, šli „went” (sometimes written was išel etc.). This goes for its compounds as well: pojdti > pošel, vojdti > všel, etc.

Additional past tenses

Old Church Slavonic, as well as most South Slavic languages, uses a more complex solution, distinguishing between the imperfect, perfect, pluperfect and aorist tenses. Interslavic projects in the 19th century tend to follow this model. In modern Interslavic, we simplify this system somewhat by merging the imperfect with the aorist, a solution that is justified by their similarity in endings. Distinguishing between various past tenses is not necessary, but allows the writer to be more specific about the precise sequence of events, and in addition, it allows some stylistic variation, too.

A word of warning is in place, though. For a vast majority of Slavs, the endings of the simple past are not understandable at all. In communication with Poles, Russians etc. it is wiser to avoid them altogether. Besides, to avoid confusion, it is better not to use them if you don't know precisely how to use them, even in communication with South Slavs.

Simple past tense

The simple past denotes an action that took place somewhere in the past. It fulfills the role of an imperfect tense and is formed by adding the following endings to the infinitive stem:


infinitive dělati nesti hvaliti
infinitive stem děla- nes- hvali-
ja dělah neseh hvalih
ty dělaše neseše hvališe
on/ona/ono dělaše neseše hvališe
my dělahmo nesehmo hvalihmo
vy dělaste neseste hvaliste
oni/one dělahu nesehu hvalihu

Perfect tense

The perfect tense is identical to the aforementioned compound past: it combines the L-participle with the present tense of the verb byti „to be”. However, within the three-way distinction between imperfect, perfect and pluperfect, its meaning is narrowed down to an action performed in the past as reflected in the present: ja jesm dělal „I have been doing”, ja jesm sdělal „I have done”.

Pluperfect tense

At last, the pluperfect tense is formed by combining the L-participle with the past (simple or compound) tense of byti. Unlike in the case of the perfect tense, the moment of reflection is in the past and refers to an action performed before that: ja běh dělal or ja byl jesm dělal „I had done”.

Future tense

The future tense is formed by combining the future tense of the verb byti „to be” with the infinitive. The forms are the same as if a verb with the stem bud- were conjugated in the present tense. Examples:

infinitive dělati
ja budu dělati
ty budeš dělati
on/ona/ono bude dělati
my budemo dělati
vy budete dělati
oni/one budut dělati

Using the present tense of a perfective verb for the future (as is done in West and East Slavic) is rather to be avoided, as it can easily be misunderstood by South Slavs.


The conditional is be formed by using the L-participle with the conditional of byti „to be”: ja byh dělal(a) „I would do”.

infinitive stem
ja byh dělal(a)
ty bys dělal(a)
by dělal
by dělala
by dělalo
my byhmo dělali
vy byste dělali
oni/one by dělali

A past conditional can be formed by inserting the paste tense of the verb „to be” into the normal conditional form:


The imperative has forms for the 2nd person singular, the 1st person plural and the 2nd person plural: dělaj „do!” (to one person, informal), dělajmo „let's do!”, dělajte „do!” (to more persons, or to one person formal). It is formed by adding -i to the present tense stem (-j after a vowel, after j). Examples:

First conjugation Second conjugation
infinitive dělati nesti hvaliti
present-tense stem dělaj- / děla- nes- hval-i-
2sg. dělaj nesi hvali
1pl. dělajmo nesimo hvalimo
2pl. dělajte nesite hvalite

Interslavic has no imperatives in the third person. When such a form is needed, the optative particle nehaj is used: Nehaj umre! „Let him die!” Nehaj žive dolgo! „May he live long!”

To distinguish the imperative from the indicative, it deserves recommendation to move accentuation to the ending. This goes especially for verbs with the imperative ending -i/-imo/-ite: prósi „asks”, prosí „ask!”

Participles and gerund

Except for the aforementioned L-participle, there are four participles in Interslavic: present active, present passive, past active, past passive.

The present active participle is derived from the present tense stem of an imperfective verb, adding -uči in the first conjugation and -eči in the second. In other words, it is built by replacing the ending -t of the 3rd person plural by -či. For example: dělati > dělajuči „doing”, hvaliti > hvaleči „praising”. It is inflected like an adjective of the soft type: běgajuči muž „the running man”, ljubeča mati „a loving mother”.
The adverbial present active participle (also known as „transgressive”) has the same ending, but is not inflected for gender: Iduči do raboty, ona vsegda dymi cigaretoju „While going to her work, she always smokes a cigarette”.

The past active participle is based on the infinitive stem of a perfective verb, followed by -vši if it ends in a vowel or -ši if it ends in a consonant. For example: sdělati > sdělavši „having done”, ukrasti (< ukrad-ti) > ukradši „having stolen”. Like the present active participle, it can both be adjectival and adverbial, but its usage as an adjective is very rare. Note that the past active particple is a very bookish form that exists in most Slavic languages, but is hardly ever used in spoken Slavic.

The present passive participle is derived from the present tense stem as well, adding -omy (-emy after a soft consonant) in the first conjugation and -imy in the second: dělajemy „being done”. It should be understood that in most Slavic languages, this participle is not used at all, whereas remnants of it can have slightly different meanings, for example vidimy means „visible” rather than „being seen”.

The past passive participle is formed by adding -ny to the infinitive stem when the latter ends in a vowel, and -eny when it ends in a consonant: dělany „done”, neseny „carried”. However:

A verb can very simply be converted into a noun (gerund, verbal noun) by substituting the ending -ny of the perfect past participle by -nje (or -ty by tje). Examples: dělanje „(the act of) doing”, pitje „drinking”.


First conjugation Second conjugation
infinitive dělati nesti hvaliti
infinitive stem děla- nes- hvali-
present-tense stem dělaj- / děla- nes- hval-i-
present active part. dělajuči nesuči hvaleči
present passive part. dělajemy / dělamy nesomy hvalimy
past active part. dělavši nesši hvalivši
past passive part. dělany neseny hvaljeny
gerund dělanje nesenje hvaljenje

The passive voice

The passive voice is created by combining a form of the verb byti „to be” with a passive participle. In the present tense, this participle can be the past passive participle or the present passive participle of an imperfective verb:

Irregular verbs (Neregularne glagoly)


The only truly irregular verb is byti „to be”. It is conjugated as follows:

present simple past (imperfect) compound past (perfect) future conditional imperative
ja jesm běh jesm byl(a) budu byh
ty jesi běše jesi byl(a) budeš bys budi
jest (je) běše (bě) byl
bude by
my jesmo běhmo byli jesmo budemo byhmo budimo
vy jeste běste byli jeste budete byste budite
oni/one sut běhu byli budut by
present active part. suči
infinitive byti past active part. byvši
gerund bytje future active part. buduči

Dati, jesti, věděti

The verbs dati „to give”, jesti „to eat” and věděti „to know” have an irregular present tense. Like byti, they belong to the so-called athematic conjugation, meaning that they have their root ending in a vowel. In the present tense, they are inflected as follows:

infinitive dati jesti věděti
present-tense stem da- je- vě-
ja dam jem věm
ty daš ješ věš
on/ona/ono da je
my damo jemo věmo
vy date jeste věte
oni dadut jedut vědut

All other forms of these three verbs are formed regularly.


The verb idti „to go” is conjugated regularly, except for the L-participle šel (f. šla, n. šlo) and the (related) past active participle šedši. Sometimes these forms are preceded by i-: išel, išla etc.

The infinitive idti is sometimes written iti.