Jotation of stem consonants

By now you have met plenty of forms that seem to have the wrong consonant: mlađi comes from mlad, rođen from roditi, pišem from pisati, vođenje from voditi. So far you learned them one by one. They are not irregular at all — they are all the result of one single sound change, and once you see it, you can walk back from almost any of these forms to the word you already know.

What happens

Many Serbian endings begin with a j sound: the comparative -ji, the old -jen of the passive participle and the verbal noun, the possessive -ji, and the -je- of some present tenses. Serbian does not like a consonant sitting right before that j. Instead of saying mlad-ji, the d and the j melt together into one new, 'softer' consonant: đ — mlađi. The j disappears, and the consonant changes. This melting is called jotation (jotovanje).

The six places you meet it

In the present tense this happens to a group of a-verbs whose present is built with -je-: you say pisati but pišem, pišeš, piše; plakati but plačem, plačeš, plače. The whole present keeps the soft consonant; the infinitive and the past (pisao, plakao) do not.

With verbs, jotation often links the two members of an aspect pair. The perfective vratiti (give back once) has an imperfective partner vraćati (be giving back, give back regularly): the t has become ć. In the same way platiti → plaćati, zaboraviti → zaboravljati, oprostiti → opraštati (here st becomes št, and the vowel changes too).

The real skill: reading backwards

You will rarely need to build these forms yourself — the ones you need are learnt with the word. What you need is to recognise them. When you see a soft consonant in a form, undo the table:

• ć → probably t: plaćati → platiti, ljući → ljut
• đ → d: rođen → roditi, mlađi → mlad
• č → k or c: jači → jak, plačem → plakati, ptičji → ptica
• ž → z or g: kažem → kazati, draži → drag
• š → s or h: nošenje → nositi, tiši → tih
• šć or št → st: gušći → gust, opraštati → oprostiti
• plj, blj, vlj, mlj → drop the l: skuplji → skup, riblji → riba, pravljenje → praviti

The commonest slip is keeping the extra l. In skuplji, gubljenje, zaboravljati the l is not part of the word — it is what jotation adds after p, b, v and m. The base words are skup, gubiti, zaboraviti. Look up the word without it.

Not every form jotates. Many comparatives use -iji and keep the consonant untouched (nov → noviji, star → stariji), and many verbs have no jotation anywhere. Treat this lesson as a key for reading forms you meet, not as a machine for making new ones — when you need a form, learn it from the word.