The Italian word certo is a small masterclass in how Italian uses adjective position to encode meaning. Sit certo before the noun and it means "a certain / a particular" — vague, indefinite identification. Sit certo after the noun and it means "certain / sure / definite" — confirmed, reliable. Un certo signor Rossi is "a certain Mr. Rossi" (someone we don't know well). Una cosa certa is "a sure thing" (something confirmed). Same word, two readings, distinguished entirely by where it sits.
This page works through the position-meaning rule for certo, the related contrast in the plural (certe persone vs persone certe), and the parallel determiner alcuno — once a workhorse for "some" but now retired in modern Italian to a single niche: negative formulas like senza alcun dubbio ("without any doubt") and elevated literary register.
1. Inflection of certo
Certo is a regular four-form adjective.
| Form | Gender + number | Example |
|---|---|---|
| certo | m. sg. | un certo Marco |
| certa | f. sg. | una certa stanchezza |
| certi | m. pl. | certi giorni |
| certe | f. pl. | certe persone |
Like other position-sensitive adjectives, the agreement is the same in both pre- and post-nominal positions. Only the meaning shifts.
2. certo before the noun: "a certain / a particular"
When certo appears between an indefinite article and a noun, it identifies the noun vaguely — the speaker either does not know exactly which one, does not want to say, or wants to leave it slightly mysterious. English uses "a certain" in the same role: a certain Mr. Rossi, a certain charm, a certain disappointment.
Ha telefonato un certo signor Rossi mentre eri fuori.
A certain Mr. Rossi called while you were out. (the speaker doesn't know him personally)
Ho una certa stanchezza dopo la riunione di stamattina.
I have a certain tiredness after this morning's meeting. (vague, hard to pin down precisely)
C'è un certo fascino nelle vecchie città italiane.
There's a certain charm to old Italian cities.
Mi ha dato una certa delusione la sua risposta.
His answer gave me a certain disappointment. (a specific kind, hard to articulate)
The pre-nominal certo almost always pairs with the indefinite article (un certo, una certa). Pairing with the definite article — il certo signore — is ungrammatical or, at best, marked.
The pre-nominal use is also the way Italians introduce a person whose name they know but who is not personally known to either speaker. Un certo Garibaldi ti ha lasciato un messaggio literally translates as "a certain Garibaldi left you a message" but practically means "some guy named Garibaldi left you a message."
Vorrei parlare con un certo professor Bianchi.
I'd like to speak with a certain Professor Bianchi. (formal — the speaker doesn't claim to know him)
3. certo after the noun: "certain / sure / confirmed"
When certo moves to the post-nominal slot, the meaning flips to the more literal "certain, sure, definite, confirmed." This is the certo that pairs with mathematical or logical certainty, with reliable people, with verified facts.
Una cosa certa è che non possiamo continuare così.
One sure thing is that we can't go on like this.
Per me è una vittoria certa, non c'è bisogno di preoccuparsi.
For me it's a certain victory, there's no need to worry.
Non abbiamo notizie certe sulla data di consegna.
We don't have any definite news about the delivery date.
Ha una conoscenza certa del settore, te lo posso garantire.
He has a sure knowledge of the field, I can guarantee you that.
The post-nominal certo answers the question "Sei sicuro?" — "Are you sure?" — and is interchangeable with sicuro in many contexts. Una cosa certa and una cosa sicura both translate "a sure thing," with certo leaning slightly more formal.
4. The position-meaning rule, side by side
This is the moment to study both readings together. The contrast is one of the cleanest position-meaning pairs in Italian.
| Phrase | Position | Meaning |
|---|---|---|
| un certo Marco | before noun | a certain Marco (vague identification) |
| un Marco certo | after noun (rare) | (non-idiomatic — would mean "a sure Marco," nonsensical) |
| una certa risposta | before noun | a certain (i.e., particular, specific) answer |
| una risposta certa | after noun | a sure / definite answer |
| certe persone | before noun | certain people (vague — "some people") |
| persone certe | after noun | certain / reliable people (trustworthy) |
| una certa vittoria | before noun | a particular / partial victory |
| una vittoria certa | after noun | a sure / guaranteed victory |
Certe persone non capiranno mai. — Le persone certe sono difficili da trovare.
Some people will never understand. — Reliable people are hard to find. (Two completely different statements, distinguished only by position.)
Avevo una certa paura prima dell'esame, ma il risultato era una vittoria certa.
I had a certain fear before the exam, but the result was a sure victory. (Both readings in one sentence — pre-nominal vague vs post-nominal definite.)
5. Plural certi / certe — vague identification
The plural certi / certe before a noun is enormously useful in everyday Italian. It means "some (specific but unnamed)" — a deliberately vague reference to a subset that the speaker has in mind but isn't naming. English equivalents include "certain people," "some folks," "a certain kind of."
Certe sere preferisco stare a casa a leggere.
Some evenings (lit. 'certain evenings') I prefer to stay home and read.
Certi vicini fanno un rumore incredibile la notte.
Some neighbors make an incredible amount of noise at night. (the speaker has specific neighbors in mind)
Ci sono certe abitudini che non riesco a perdere.
There are certain habits I can't manage to break.
Certi giorni sono più difficili di altri.
Some days are harder than others.
This plural use is more than just a fuzzy quantifier — it carries a tone. Certe persone often comes with raised eyebrows or a mild grimace; the speaker has a specific group in mind and is criticizing them obliquely. Certe sere implies "those particular evenings I'm thinking of, which we both know about."
The contrast with alcune persone ("some people" — neutrally indefinite) is real: certe persone is the version with attitude.
Certe cose è meglio non saperle.
Some things are better left unknown. (the proverbial 'certain things')
6. The post-nominal plural: persone certe — "reliable / trustworthy"
The post-nominal certi / certe maintains the "sure / certain" reading and is most often translated as "reliable, trustworthy, confirmed." This use is much rarer than the pre-nominal vague reading and tends to appear in formal, journalistic, or technical contexts.
Per concludere l'affare ci servono notizie certe sui finanziamenti.
To close the deal we need reliable news about the financing.
Solo dati certi possono giustificare una decisione del genere.
Only definite data can justify a decision like this.
Ho fonti certe — non sto inventando niente.
I have reliable sources — I'm not making anything up.
In casual conversation, Italians lean on sicuro (post-nominal certo's near-synonym) for this meaning: fonti sicure, dati sicuri, notizie sicure. The post-nominal certo is somewhat more literary.
7. certo as an adverbial — "of course"
Certo also functions as an adverb meaning "certainly / of course / sure" — invariable in this use, often as a one-word answer or a sentence-initial affirmation. This use is everywhere in conversation.
— Posso usare il tuo telefono? — Certo, fai pure.
— Can I use your phone? — Of course, go ahead.
Certo che ti aiuto, non c'è bisogno di chiederlo.
Of course I'll help you, there's no need to ask.
Lo conosco, certo, lavoriamo insieme da dieci anni.
I know him, sure, we've worked together for ten years.
The fixed phrase certo che + clause ("of course (it's the case that)…") is a casual way to give emphatic agreement.
8. alcuno: the retired determiner
Alcuno in singular ("any") was once a workhorse of Italian — the equivalent of "any" in negative contexts and a partner to qualche in affirmative ones. In modern Italian it has largely retired, surviving in two specific niches:
Niche 1: with negation, especially in fixed formulas like senza alcun, senza alcuna
In negative contexts, singular alcuno still appears as a more emphatic equivalent of nessuno. The most common formula is senza alcun + noun ("without any + noun"), which is heard and read constantly in modern Italian.
L'ho fatto senza alcun dubbio.
I did it without any doubt.
È stata una scelta senza alcuna esitazione.
It was a choice without any hesitation.
Non ho alcun problema a ripeterlo.
I have no problem at all repeating it. (literary feel)
La proposta non presenta alcun vantaggio per noi.
The proposal presents no advantage for us. (formal/written register)
The form alcun before a consonant follows the same truncation rule as uno / un and nessuno / nessun: alcun dubbio, alcun problema, alcun motivo. Before a feminine word, the unelided form alcuna applies: alcuna esitazione, alcuna preoccupazione. Before a masculine vowel, alcun appears: alcun amico, alcun errore.
Niche 2: literary / archaic affirmative use
In older texts, in poetry, and in deliberately elevated prose, alcuno in the singular still appears in affirmative sentences with the meaning "some / any."
In alcun modo riusciremo a convincerlo.
In some way we will manage to convince him. (literary — modern Italian would say 'in qualche modo')
Vi sarà alcun rimedio?
Will there be any remedy? (archaic / literary)
In modern conversational Italian, this use is dead. You will read it in nineteenth-century literature and in occasional formal modern writing, but you should not produce it. The everyday equivalents are qualche for "some" in affirmative sentences and nessun for "no / any" in negative ones.
9. The plural alcuni / alcune — alive and well
While singular alcuno has retired, the plural alcuni / alcune is fully alive and means "some / a few" — the standard plural counterpart to qualche.
Ho letto alcuni libri sull'argomento.
I've read some books on the subject.
Alcune mie amiche vivono in Francia.
Some of my (female) friends live in France.
Alcuni studenti hanno chiesto di rimandare l'esame.
Some students asked to postpone the exam.
For the full treatment of qualche and alcuni, see the dedicated page on those determiners. The point here: only the singular alcuno has retreated to negative-and-literary niches; the plural alcuni / alcune is everyday Italian.
Common Mistakes
❌ Una risposta certa al mio problema. (in the sense of 'a particular answer')
The post-nominal certa means 'sure / definite,' not 'a particular.' If you want 'a particular answer,' use pre-nominal: una certa risposta.
✅ Una certa risposta al mio problema. / Una risposta certa al mio problema.
A particular answer to my problem. / A definite answer to my problem. (Different meanings — choose by position.)
❌ In nessun modo, senza nessun dubbio. (using nessun twice in one sentence)
Stylistically clumsy — vary the negation. Use senza alcun dubbio for variety and elevation.
✅ In nessun modo posso accettare, senza alcun dubbio.
In no way can I accept, without any doubt.
❌ Ho letto alcuno libro interessante.
Wrong — singular alcuno in affirmative contexts is archaic. Use qualche libro or some other determiner.
✅ Ho letto qualche libro interessante. / Ho letto alcuni libri interessanti.
I've read some interesting books.
❌ Senza alcuno dubbio.
Wrong — alcuno truncates to alcun before a consonant, the same way uno truncates to un.
✅ Senza alcun dubbio.
Without any doubt.
❌ Ha telefonato il certo signor Rossi.
Wrong — pre-nominal certo (vague identification) almost always takes the indefinite article, not the definite.
✅ Ha telefonato un certo signor Rossi.
A certain Mr. Rossi called.
❌ Persone certe non capiranno mai. (intending 'some people')
Wrong word order for the intended meaning — post-nominal certe means 'reliable,' not 'some.' Move certe before the noun.
✅ Certe persone non capiranno mai.
Some (kinds of) people will never understand.
Key takeaways
- Certo before the noun = "a certain / a particular" — vague, indefinite identification. Pairs with the indefinite article: un certo signore, una certa stanchezza, certi giorni.
- Certo after the noun = "certain / sure / definite" — confirmed, reliable. Una cosa certa, fonti certe.
- The plural certi / certe before the noun is a workhorse of conversational Italian, often translated "some," but with a tone — the speaker has specific people or things in mind and may be criticizing or singling them out.
- The adverbial certo (invariable) means "of course / certainly" as an emphatic affirmation: Certo, fai pure.
- Singular alcuno has retired in modern Italian. It survives in negative formulas (senza alcun dubbio, non…alcun motivo) and in elevated literary register. The plural alcuni / alcune remains everyday Italian.
- Truncation: alcuno → alcun before a consonant or masculine vowel; feminine alcuna before consonant, alcun' almost never used.
For the broader pattern of position-meaning shifts, see Adjectives: Meaning Change by Position. For the partner determiners qualche and alcuni, see qualche and alcuni. For other position-sensitive determiners, see stesso and medesimo and diverso, parecchio, vario. For the wider determiner architecture, see Determiners: Overview.
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