This is the first part of the lesson. The rest, the exercises and the reviews are in the app.
The infinitive and the two verb stems
You already know nouns by their dictionary form. Verbs have one too, and it is called the infinitive: raditi “to work, to do”, čitati “to read”, videti “to see”. It is the form you look up, and the point from which we count every other form of the verb. Where English needs two words, “to” plus the verb, Serbian needs one: the ending -ti does the job of “to”.
But the Serbian verb has a feature worth understanding before any conjugation: it has not one stem but two. One is visible in the infinitive, the other in the present tense, and very often they look different. You know the idea from English irregular verbs such as sing, sang, sung; Serbian does something similar, but systematically. This lesson is not about conjugating (the lesson “Present tense” does that) but about the skeleton: what the infinitive is, where the two stems come from and what is built on which. Once you have it, you will stop being surprised that pisati “to write” suddenly gives pišem “I write”.
The two infinitive endings: -ti and -ći
The overwhelming majority of Serbian infinitives end in -ti. A small but very frequent handful end in -ći; this is an old closed class, and new verbs never join it. (Remember the sound: ć is a soft “ch”, close to the t in British tune.)
Learn these two “tails” and you will always spot an infinitive in a text: if a word ends in -ti or -ći and comes after a word meaning “I want”, “I can” or “one must”, you are almost certainly looking at the dictionary form of a verb.
Where you will meet the infinitive
An infinitive rarely stands alone; it usually hangs on another word: most often a verb such as “must”, “can”, “want”, “begin”, or an impersonal word like “one needs to”, “one may”, “one mustn’t”:
The infinitive also serves as an impersonal command on signs, in recipes and in instructions addressed to everyone at once. Ne pušiti! is “No smoking!”; Gurati and Vući on doors are “Push” and “Pull”.
Why a verb has two stems
Now the main point. Every verb form is built on a stem: what is left when you take the ending off. The catch is that there are two stems, taken from different places:
The infinitive stem (Serbian infinitivna osnova) is what is left of the infinitive without -ti: čita-, radi-, vide-, pisa-. With the -ći verbs you cannot cut it out like that: the ending has swallowed the end of the stem, which only shows in other forms (moći, mogu).
The present stem (prezentska osnova) is the part all present-tense forms share, what is left without the personal endings: rad- in radim “I work”, radiš “you work”, rade “they work”; piš- in pišem “I write”, pišeš “you write”.
Cheat sheet
The cheat sheet — everything essential from the lesson on one page. In the app it opens at any time.
The infinitive and the two verb stems
The infinitive is the dictionary form of a verb (“to do”); the ending does the job of English “to”. It says nothing about person or time. Only two endings: -ti for the vast majority, -ći for a small closed class.