κάτι vs κάποιος | Greek Grammar

The shapes of these two words are settled business: κάποιος declines like an adjective, κάτι never changes, and κάτι has a second life in front of a plural noun. All of that, with the paradigm, is on μερικοί, κάποιος, κάτι. This page is about something you cannot look up in a table — the decision you make mid-sentence about which one to say, and what that decision tells your listener about how much you know.

Two questions settle it, and they are not the same question. Is the referent a person? And could you identify it if you had to?

Standing alone, κάποιος is a person and κάτι is not

Used as a bare pronoun, with no noun after it and nothing in the conversation for it to stand for, κάποιος means somebody — a human being, and κάτι means something, and not a human being. There is no overlap and no third option: Greek gives you no bare pronoun that is neutral between the two the way English someone or something has to be spelled out.

Κάποιος πήρε να ρωτήσει για το διαμέρισμα, θα ξαναπάρει το απόγευμα.

kápios píre na rotísi ya to dhiamérizma, tha ksanapári to apóyevma

Somebody rang to ask about the flat — he'll call again this afternoon.

Θέλω να σου δείξω κάτι, έλα λίγο.

thélo na su dhíkso káti, éla lígho

I want to show you something — come here a sec.

Three qualifications, because the rule as stated is about the bare pronoun and nothing else. First, κάποιος with a noun reaches things perfectly happily — κάποιο βιβλίο, κάποια λύση, κάποιο πρόβλημα — because the noun, not the pronoun, is carrying the reference. Second, the colloquial κάτι that sits in front of a plural noun can absolutely head a human one — κάτι παιδιά, κάτι τύποι — but that is the vague-quantifier construction covered on the μερικοί page, not the pronoun. Third, when a noun has already been mentioned, κάποιος can pick it up whatever it is: Έχω τρεις φορτιστές, πάρε κάποιον is a charger, not a person, because there is an antecedent standing behind the pronoun. The animacy split is about κάτι and κάποιος with nothing behind them.

Could you name it? κάποιος says yes

Here is the deeper half of the split, and it is the part that makes Greek speakers sound Greek. κάποιος presupposes that there is one particular individual. Somebody definite exists; the speaker simply is not supplying the name — either because they do not know it, or, very often, because they have decided not to say it. That second use is a piece of social machinery: κάποιος is how you attribute information without naming a source.

Μου το είπε κάποιος που δουλεύει εκεί, αλλά δεν θα σου πω ποιος.

mu to ípe kápios pu dhulévi ekí, alá dhen tha su po pios

Somebody who works there told me, but I'm not going to tell you who.

Ήταν κάποιος Βασιλείου από το λογιστήριο, ρώτησε για τα τιμολόγια.

ítan kápios Vasilíu apó to loyistírio, rótise ya ta timolóyia

It was a Mr Vasiliou from accounts — he was asking about the invoices.

That second sentence shows the other everyday job of κάποιος: in front of a proper name it is English a certain, and it says "this person exists, I have their name in front of me, and I assume you do not know them". Related and very high-frequency is κάποια στιγμή — "at some point", a moment that exists but has not been fixed yet.

Κάποια στιγμή θα πρέπει να του το πούμε, δεν γίνεται αλλιώς.

kápia stighmí tha prépi na tu to púme, dhen yínete aliós

At some point we're going to have to tell him — there's no way round it.

One idiom falls straight out of this "there is a particular one" logic. Είναι κάποιος — literally "he is somebody" — means he is a person of consequence, and it is almost always said with a raised eyebrow (informal).

Νομίζει ότι είναι κάποιος επειδή τον έβγαλαν στην τηλεόραση.

nomízi óti íne kápios epidhí ton évghalan stin tileórasi

He thinks he's somebody because they put him on television. (informal)

κάτι does not have to be a thing at all

κάτι carries no such promise of a particular individual. It can point at an object, but its most characteristic use is to point at an event, a situation, a change in the air — something the speaker cannot identify because it has no clear edges to identify. This is where κάτι has a whole domain that κάποιος cannot enter, and where English speakers under-use it badly.

Κάτι έγινε στο σχολείο σήμερα, αλλά δεν μου λέει τι.

káti éyine sto scholío símera, alá dhen mu léi ti

Something happened at school today, but he won't tell me what.

Κάτι τρέχει με το ίντερνετ, όλο κολλάει η σελίδα.

káti tréchi me to índernet, ólo kolái i selídha

Something's up with the internet — the page keeps freezing.

Κάτι δεν πάει καλά μαζί του τελευταία, το βλέπω.

káti dhen pái kalá mazí tu teleftéa, to vlépo

Something's not right with him lately — I can see it.

Learn those last two as shapes. Κάτι τρέχει ("something's going on") and κάτι δεν πάει καλά ("something's wrong") are the two standard ways of reporting a problem you can feel but cannot yet name, and both are built on κάτι precisely because the trouble has not been identified. Κάτι μου λέει ότι… ("something tells me that…") works the same way — an intuition is not an individual, so the idiom has no κάποιος version.

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Ask yourself what you would have to point at. If it is a person — one you could in principle put a name to — say κάποιος. If it is a situation, a noise, a feeling, a piece of news, a something-or-other with no shape, say κάτι. Watch the verb: in their "happen / be going on" sense, συμβαίνει, γίνεται, τρέχει, δεν πάει καλά need an event, so κάτι fits and κάποιος cannot. The same verbs with a human subject simply mean something else — τρέχει is "he's running", έγινε γιατρός is "he became a doctor".

κάτι is invariable — but it is neuter singular

This is the concrete grammar point of the page, and it catches learners who have heard κάτι παιδιά and concluded that κάτι is somehow plural. It is not. When it heads a plural noun, agreement follows the noun (Ήρθαν κάτι παιδιά). When it stands alone, κάτι never changes shape but behaves as a neuter singular, and everything agreeing with it follows suit: the adjective, the participle, the verb.

Πάρε κάτι κρύο από το ψυγείο, έχει και χυμό.

páre káti krío apó to psiyío, échi ke chimó

Grab something cold from the fridge — there's juice too.

Ψάχνω κάτι καινούριο να διαβάσω, βαρέθηκα τα αστυνομικά.

psáchno káti kenúrio na dhiaváso, varéthika ta astinomiká

I'm looking for something new to read — I've had enough of crime novels.

The adjective goes after κάτι, exactly as in English something cold, so the word order costs you nothing; the ending is the whole lesson. The same slot takes a relative clause (κάτι που δεν περίμενα) and the comparison word σαν, which is how Greek says "something like a…".

Είναι κάτι σαν καφενείο, αλλά σερβίρουν και φαγητό.

íne káti san kafenío, alá servírun ke fayitó

It's something like a café, but they do food as well.

There is one further pattern that has no English counterpart at all. Slip the neuter article in — κάτι το + adjective — and you get "a certain quality of X-ness", a way of attributing an atmosphere to something without claiming to have analysed it.

Έχει κάτι το γοητευτικό αυτή η πόλη τον χειμώνα.

échi káti to ghoiteftikó aftí i póli ton chimóna

There's something enchanting about this city in winter.

Under a negation, and in a question

The default swap is not this page's business: in a plain negation κάτι becomes τίποτα and κάποιος becomes κανένας, with an obligatory δεν, and that rule with its examples is on μερικοί, κάποιος, κάτι and negative polarity. What belongs here is the escape hatch, because it follows directly from the specificity logic above.

When the negation is aimed not at whether the thing exists but at what kind of thing it is, κάτι and κάποιος stay. The modifier is what is being denied; the existence is conceded.

Δεν είπε κάτι συγκεκριμένο, μόνο ότι θα το ξανασκεφτεί.

dhen ípe káti singekriméno, móno óti tha to ksanaskeftí

He didn't say anything specific, just that he'd think about it again.

Δεν έχω κάτι καλύτερο να προτείνω, οπότε ας το κάνουμε έτσι.

dhen écho káti kalítero na protíno, opóte as to kánume étsi

I haven't got anything better to suggest, so let's do it that way.

Both of those concede that he did say things and that suggestions do exist — the denial lands on συγκεκριμένο and on καλύτερο. Strip the modifier away and the escape hatch closes: for a flat "he said nothing" you are back to δεν είπε τίποτα.

In a question both series are grammatical, and the choice is one of expectation rather than of rules. κάποιος leans towards a yes; κανείς leaves the door open, and is what you will hear more often in casual speech.

Πήρε κάποιος όσο ήμουν στο μπάνιο;

píre kápios óso ímun sto bánio;

Did somebody ring while I was in the shower? (I half expect that they did)

Πήρε κανείς όσο ήμουν στο μπάνιο;

píre kanís óso ímun sto bánio;

Did anyone ring while I was in the shower? (genuinely open — the everyday version)

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Under a negation, ask what the δεν is aimed at. Denying that anything exists at all — I saw nothing, nobody came — forces the swap to τίποτα / κανένας. Denying a property while conceding the thing — nothing specific, nothing better — leaves κάτι / κάποιος in place, because the adjective is what the negation is really biting.

Common Mistakes

1. Using κάτι for a person. The bare pronoun is never human, however unidentified the person is.

❌ Κάτι σε ζητάει στην είσοδο.

Incorrect — a human referent takes κάποιος; bare κάτι cannot denote a person.

✅ Κάποιος σε ζητάει στην είσοδο, λέει ότι είναι από την πολυκατοικία.

kápios se zitái stin ísodho, léi óti íne apó tin polikatikía

There's somebody at the door for you — says he's from the building.

2. Using κάποιος for an event. Only κάτι can be the thing that happens; κάποιος promises an individual, and an individual cannot occur.

❌ Κάποιος συνέβη χθες βράδυ στη γειτονιά και ήρθε η αστυνομία.

Incorrect — the subject of συμβαίνει is an event, so it must be κάτι.

✅ Κάτι συνέβη χθες βράδυ στη γειτονιά και ήρθε η αστυνομία.

káti sinévi chthes vrádhi sti yitoniá ke írthe i astinomía

Something happened in the neighbourhood last night and the police turned up.

3. Leaving the adjective after κάτι in its dictionary form. κάτι does not inflect, but what follows it must — into the neuter singular.

❌ Μου συνέβη κάτι περίεργος στον δρόμο.

Incorrect — anything agreeing with κάτι goes neuter singular: κάτι περίεργο.

✅ Μου συνέβη κάτι πολύ περίεργο στον δρόμο για τη δουλειά.

mu sinévi káti polí períergho ston dhrómo ya ti dhuliá

Something really odd happened to me on the way to work.

4. Reaching for the neuter because English "someone" has no gender. For a person whose gender you do not know, Greek defaults to the masculine κάποιος — the neuter κάποιο is only available when there is a neuter noun in the discourse for it to stand for.

❌ Κάποιο άφησε αυτόν τον φάκελο για σένα.

Incorrect — a human referent of unknown gender takes masculine κάποιος, not neuter κάποιο.

✅ Κάποιος άφησε αυτόν τον φάκελο για σένα στην υποδοχή.

kápios áfise aftón ton fákelo ya séna stin ipodhochí

Somebody left this envelope for you at reception.

Key Takeaways

With nothing behind it — no noun, no antecedent — κάποιος is a person and κάτι is not a person. Give either of them a noun or an antecedent and the picture changes: κάποιο βιβλίο is a thing, and colloquial κάτι παιδιά is people.
κάποιος promises that one particular individual exists — the speaker either cannot name them or has chosen not to. Hence κάποιος Βασιλείου ("a certain Vasiliou"), κάποια στιγμή, and the wry Είναι κάποιος (informal).
κάτι can point at something with no edges — an event, a fault, a feeling. Κάτι έγινε, Κάτι τρέχει, Κάτι δεν πάει καλά, Κάτι μου λέει ότι… have no κάποιος counterpart.
Standing alone, κάτι is invariable but neuter singular, and everything agreeing with it follows suit — κάτι κρύο, κάτι καινούριο, and the atmospheric κάτι το + adjective (κάτι το γοητευτικό). In front of a plural noun, agreement goes with the noun instead.
A negation aimed at a modifier rather than at existence lets both words survive: Δεν είπε κάτι συγκεκριμένο. Take the modifier away and the ordinary swap to τίποτα / κανένας applies again.
In a question both are correct: Πήρε κάποιος; expects a yes, Πήρε κανείς; is open and more colloquial.

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