When you want to point at a person or thing without saying which one — someone knocked, I want something, a few people left — English reaches for a small set of frozen words: someone, something, a few, many. Finnish has its own set, and the single most important thing to learn about them is that Finnish forces a choice English never makes: is the unspecified referent a person or a thing? joku is for people, jokin is for things, and picking the wrong one is a real grammatical error, not just a stylistic slip.
joku (someone) vs jokin (something)
This is the core distinction. joku refers to an unspecified person; jokin refers to an unspecified thing, phenomenon, or fact. English "someone/somebody" and "something" line up neatly with them — the trap is that in everyday speech Finns often blur the two, so learners hear both and lose the rule.
Joku soitti ovikelloa.
Someone rang the doorbell.
Jokin haisee pahalta keittiössä.
Something smells bad in the kitchen.
Read them as a minimal pair. Swap joku for jokin in the first sentence and you are no longer talking about a person — you have made the doorbell-ringer into an unidentified thing, which is not what you mean. The choice is animate (person) vs inanimate (thing), and it is grammatical.
Both pronouns inflect — and joku inflects in two places
Here is the feature that surprises every learner. These are not frozen words. When the sentence needs a case, the pronoun takes it — and with joku, both halves of the word decline at once. The front part behaves like the case-marked pronoun jo- and the back part -ku echoes the same case. With jokin, only the front part inflects; the -kin stays put as a fixed clitic.
| Case | joku (person) | jokin (thing) |
|---|---|---|
| Nominative | joku | jokin |
| Genitive | jonkun | jonkin |
| Partitive | jotakuta (~ jotain) | jotakin (~ jotain) |
| Inessive (in) | jossakussa | jossakin (~ jossain) |
| Illative (into) | johonkuhun | johonkin |
| Adessive (at/with) | jollakulla | jollakin (~ jollain) |
| Allative (to) | jollekulle | jollekin |
Notice jonkun vs jonkin: for a person the -ku becomes -kun; for a thing the -kin is unchanged. And notice the everyday contracted forms in parentheses — jotain, jossain, jollain — which you will hear far more often than the full jotakin, jossakin, jollakin in speech, though the long forms are standard in writing.
Näin jonkun kurkistavan ikkunasta.
I saw someone peeking out of the window.
Haluan juoda jotakin kylmää.
I want to drink something cold.
Etsin jotakuta, joka osaisi korjata polkupyörän.
I'm looking for someone who could fix a bicycle.
In the last sentence the person is in the partitive because etsiä ("look for") governs the partitive object — and joku answers with its own partitive, jotakuta. The pronoun bends to the same grammar as any noun would.
eräs — a certain (specific but unnamed)
eräs means "a certain (one)": the speaker has a specific referent in mind but does not name it. It is the natural word for storytelling and introductions, slightly more literary than the plain yksi ("one, a"). It declines like an ordinary -s word: eräs, erään, erästä, eräässä.
Eräs vanha mies pysäytti minut kadulla.
A certain old man stopped me on the street.
Tapasin erään ystäväni kaupungilla eilen.
I ran into a friend of mine downtown yesterday.
The difference between joku mies and eräs mies is that joku means the speaker genuinely does not know who, while eräs means the speaker knows but is leaving it vague — much like English "some man came" vs "a certain man came."
muutama — a few
muutama means "a few, a couple of." Its defining quirk for English speakers: it is grammatically singular and takes a singular noun, even though it means more than one.
Muutama vieras jäi vielä juttelemaan.
A few guests stayed on to chat.
Ostin torilta muutaman omenan.
I bought a few apples at the market.
Literally that first sentence is "a-few guest stayed" — vieras is singular. This is because muutama, like the numbers, counts its noun as a single quantified block. (The same logic drives the number + partitive singular pattern.)
moni — many a (counted one by one)
moni means "many," but it pictures the many as individuals counted one by one, so — like muutama — it takes a singular noun and a singular verb: moni ihminen ("many a person"), not moni ihmiset. It also has an irregular partitive, monta, which is a topic in its own right.
Moni suomalainen ei osaa ruotsia hyvin.
Many Finns can't speak Swedish well.
Moni ei tiennyt, mitä sanoa.
Many didn't know what to say.
Both take singular agreement — ei osaa, ei tiennyt — because moni itself is singular. When you want the plural "many" as a bulk group, Finnish switches to monet (plural) or monta (the counting form). The full moni / monta / monet split has its own page: moni vs monta. For "each/every," "all" and other universal quantifiers such as jokainen and kaikki — which likewise force singular or plural agreement — see quantifying pronouns.
Common Mistakes
❌ Jokin koputti oveen.
Incorrect — a person knocked, so use joku, not jokin (which means a thing).
✅ Joku koputti oveen.
Someone knocked on the door.
❌ Haluan syödä joku.
Incorrect — 'something' to eat is a thing, and the object needs the partitive: jotakin.
✅ Haluan syödä jotakin.
I want to eat something.
❌ Moni ihmiset olivat väsyneitä.
Incorrect — moni takes a singular noun and singular verb, not a plural.
✅ Moni ihminen oli väsynyt.
Many people were tired.
❌ Näin joku pihalla.
Incorrect — as an object 'someone' takes the accusative/genitive form: jonkun.
✅ Näin jonkun pihalla.
I saw someone in the yard.
❌ Asun jonkin kanssa.
Incorrect — for living with a person, use the person-word jonkun (genitive of joku), not the thing-word jonkin.
✅ Asun jonkun kanssa.
I live with someone.
Key Takeaways
- joku = someone (person), jokin = something (thing). The animate/inanimate split is grammatical, not optional.
- Both pronouns inflect for case; with joku both halves change (jonkun, jotakuta, jollekulle), while jokin keeps its -kin fixed (jonkin, jotakin, jollekin).
- Everyday speech contracts jokin's oblique forms: jotain, jossain, jollain.
- eräs = "a certain," for a specific but unnamed referent — the storytelling word.
- muutama ("a few") and moni ("many a") both take a singular noun and singular agreement, because they count individuals.
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Start learning Finnish→Related Topics
- kaikki, jokainen, muutama, kumpikinB1 — The quantifiers that group or single out — kaikki (all, plural), jokainen (each, singular), molemmat and kumpikin (both), plus usea, moni, harva, sama and muu.
- Negative Pronouns: kukaan, mikään, mitäänA2 — kukaan (no one) and mikään (nothing) are negative-polarity pronouns — they demand a negative verb, so Finnish says 'nobody didn't come' by design.
- moni vs monta, harva vs harvatB2 — Why 'many' splits into moni (singular agreement) and monta (partitive counting), and how harva and its plural harvat divide up 'few'.
- Numbers Take the Partitive Singular: kaksi kissaaA2 — The signature Finnish counting rule — every cardinal above one governs the partitive singular of the counted noun, which stays singular: kaksi kissaa, sata euroa.