Instrumental forms

Lesson opening

This is the first part of the lesson. The rest, the exercises and the reviews are in the app.

Instrumental forms

The instrumental (instrumental) is the case of “with what” and “with whom”. You write with it (with a pen), cut with it (with a knife), travel with it (by bus), go places with it (with a friend) and say what happens regularly (in the mornings). The name gives away its main job: this is the case of the instrument, the tool, the means. But it also has a second, social life: company, being “together with someone”.

Where those two roles meet lies the main trap of this lesson, and English makes it deeper, because it uses one word for both: cut with a knife, walk with my brother. Serbian marks them differently. The tool takes the bare instrumental, with no preposition; the companion takes the preposition s/sa. Mixing them up changes the meaning: Sečem nožem is “I cut with a knife”, while Idem s nožem is “I’m walking along with a knife on me”. So once the forms are in place, we will look at the “s or no s” rule separately.

First declension: -om or -em

Masculine nouns take -om if the stem ends in a hard consonant, and -em if it ends in a soft one, that is, j, lj, nj, č, ć, dž, đ, š, ž or c. Neuter nouns show you the ending themselves: those in -o take -om, those in -e take -em:

By the same rule: gradom, bratom, prozorom (window), selom, but nožem, mužem (husband), ključem (key), krajem (end), konjem (horse), poljem (field). The split between hard and soft consonants will come back again and again in Serbian endings, so it pays to get used to it now.

Second declension (nouns in -a): -om

Nouns in -a take -om, and there is no sibilarization here (the k → c, g → z, h → s change you met in the dative, as in ruci), because that only happens before -i:

Everything here is straightforward: vodom (water), kafom (coffee), and for company sa ženom (with my wife). (Olovka is strictly a pencil, but in everyday speech it covers a pen as well.) Masculine nouns in -a go the same way: tata → tatom (dad), deda → dedom (grandad).

Third declension (feminine nouns in a consonant): -i or -ju

Feminine nouns ending in a consonant (noć, stvar, ljubav) have two instrumental forms, and both are correct. One ends in -i, like the genitive: noći, stvari. The other ends in -ju, and there the last consonant of the stem often fuses with the j and changes. This fusing is called iotation (from “jot”, the traditional name of the j sound):

Cheat sheet

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Instrumental forms

The instrumental (instrumental) answers kim? (with whom?) and čime? (with what?). Two axes: the ending, set by the declension and the softness of the stem; the preposition, set by the role.

Endings: all classes

Third declension: iotation in -ju

Roles: bare instrumental or a preposition