Presente: -isco -ire Verbs | Italian Grammar

The -isco subgroup is the larger of the two patterns within the -ire conjugation, and it's the productive default: when a new -ire verb enters Italian, it will almost always take the -isco pattern. Most -ire verbs you'll meet — finire, capire, preferire, pulire, costruire — belong to this subgroup. The list is open-ended, unlike the small closed list of pure -ire verbs.

The model verb is finire (to finish). The pattern's signature is an -isc- infix that appears in four of the six conjugated forms but not in noi and voi, which keep the plain stem.

The endings

To conjugate an -isco -ire verb in the presente, drop the -ire ending from the infinitive to get the stem. Then:

For io, tu, lui/lei, loro: insert -isc- between the stem and the ending, and add the regular -ire ending.
For noi, voi: just add the regular -ire ending. No infix.

The six forms with finire as the model:

Person	Pattern	finire
io	stem + isc + o	finisco
tu	stem + isc + i	finisci
lui / lei / Lei	stem + isc + e	finisce
noi	stem + iamo	finiamo
voi	stem + ite	finite
loro	stem + isc + ono	finiscono

Finisco di lavorare alle sei e poi vengo da te.

I finish work at six and then I'll come to you.

A che ora finisci?

What time do you finish?

Il film finisce con un colpo di scena incredibile.

The film ends with an incredible plot twist.

Finiamo questo capitolo e poi facciamo una pausa.

Let's finish this chapter and then take a break.

Ragazzi, a che ora finite la lezione?

Guys, what time does your class end?

I bambini finiscono i compiti prima di cena.

The kids finish their homework before dinner.

The shape on the page

Notice the visual rhythm: four forms with the -isc- chunk pinned in the middle, two forms (noi and voi) without it. This irregular shape is the most distinctive thing about Italian among the Romance languages — it creates a "1-2-3, gap, gap, 6" pattern in the conjugation that learners have to internalize.

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The -isco infix exists in exactly the same four forms in every -isco verb: 1st, 2nd, 3rd singular, and 3rd plural. The noi and voi forms are always plain. There are no exceptions.

Pronunciation: -sc- before different vowels

The digraph sc in Italian represents two different sounds depending on what follows:

/sk/ before -a, -o, -u, or any consonant — the hard "sk" sound
/ʃ/ before -i or -e — the soft "sh" sound

In the -isco subgroup, this means a single conjugation contains both sounds:

Form	Spelling	Sound
io	finisco	fi-NEE-sko
tu	finisci	fi-NEE-shee
lui / lei	finisce	fi-NEE-she
loro	finiscono	fi-NEE-sko-no

So as you conjugate, the sound switches from /sk/ to /ʃ/ to /ʃ/ to /sk/ across the four -isco forms. This is automatic and predictable — it's the same rule that governs all sc spelling in Italian — but it does require active practice.

Quando finisci, mi chiami?

When you finish, will you call me?

Mio fratello finisce sempre per ultimo a tavola.

My brother always finishes last at the table.

Stress on the loro form

The stress in the loro form of -isco verbs falls on the -i- of -isco: finìscono, capìscono, preferìscono. This is different from the loro form of pure -ire, -are, and -ere verbs, which all stress the root (dòrmono, pàrlano, scrìvono). The -isc- infix carries its own stress.

In all four forms with the infix, the stress pattern is consistent: fi-NEE-sko, fi-NEE-shee, fi-NEE-she, fi-NEE-sko-no. The infix itself, -ìsc-, takes the stress.

I miei nonni capiscono il dialetto, ma non lo parlano.

My grandparents understand the dialect but don't speak it.

I clienti preferiscono il pane fresco.

Customers prefer fresh bread.

For the broader picture of stress placement across all conjugations, see stress patterns in conjugations.

High-frequency -isco -ire verbs

These all take the -isco pattern. Memorize the model finire and you have all of them.

Infinitive	Meaning	io form	noi form	loro form
capire	to understand	capisco	capiamo	capiscono
preferire	to prefer	preferisco	preferiamo	preferiscono
pulire	to clean	pulisco	puliamo	puliscono
spedire	to send (mail)	spedisco	spediamo	spediscono
riunire	to gather, to meet	riunisco	riuniamo	riuniscono
costruire	to build	costruisco	costruiamo	costruiscono
stabilire	to establish	stabilisco	stabiliamo	stabiliscono
ferire	to wound	ferisco	feriamo	feriscono
colpire	to hit, to strike	colpisco	colpiamo	colpiscono
sparire	to disappear	sparisco	spariamo	spariscono
garantire	to guarantee	garantisco	garantiamo	garantiscono
definire	to define	definisco	definiamo	definiscono
impedire	to prevent	impedisco	impediamo	impediscono
favorire	to favor	favorisco	favoriamo	favoriscono

Non capisco una parola di quello che dice.

I don't understand a word of what he's saying.

Preferisco il caffè senza zucchero.

I prefer coffee without sugar.

Puliamo la casa il sabato mattina, è un'abitudine.

We clean the house on Saturday mornings, it's a habit.

Spedisco il pacco oggi pomeriggio.

I'm sending the package this afternoon.

Costruiscono una nuova scuola vicino al parco.

They're building a new school near the park.

I gatti spariscono ogni volta che arrivano ospiti.

The cats disappear every time guests arrive.

Ti garantisco che funziona, l'ho provato io stesso.

I guarantee you it works, I tried it myself.

Why -isco exists at all

If you're wondering why Italian developed this awkward-looking pattern, the answer is historical. In Latin, certain verbs had an "inchoative" suffix -sc- that originally signaled "to begin to do X" or "to gradually become X." Over centuries, that meaning faded and the suffix became a phonological feature of one branch of the third conjugation. By Old Italian, it had spread to many verbs that originally didn't have it, and it became the productive pattern: any new -ire verb defaults to -isco.

This is helpful to know because it explains a quirk: many -isco verbs do describe gradual change or completion (finire = to finish, capire = to understand, costruire = to build, definire = to define, sparire = to disappear). The original meaning of the -sc- suffix lingers in the lexicon, even though the rule is now purely formal.

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If you can't remember whether a new -ire verb is pure or -isco, default to -isco. You'll be right far more often than not.

A few useful pairs to compare

Putting -isco verbs next to pure -ire verbs side by side helps fix the contrast in your ear:

Pure -ire (no -isc-)	-isco -ire (with -isc-)
dormo (I sleep)	finisco (I finish)
parto (I leave)	capisco (I understand)
apro (I open)	pulisco (I clean)
sento (I hear)	preferisco (I prefer)
offro (I offer)	spedisco (I send)

Notice that the noi and voi forms collapse the distinction: dormiamo / finiamo, dormite / finite. Without those forms, you can hear instantly which group a verb belongs to. With them, you can't.

Capisci l'italiano, ma preferisci parlare inglese?

You understand Italian but prefer to speak English?

Pulisce la cucina ogni sera prima di dormire.

He cleans the kitchen every evening before going to sleep.

Why English speakers struggle

English has nothing remotely like an infix that appears in some forms but not others. The closest analogy might be the way English adds -es (he goes, she does), but that's a single suffix in a single form, not a four-form infix. The result is that English speakers often:

Forget the infix in noi/voi — saying finisciamo instead of finiamo. The infix never appears in those forms.
Apply the infix to pure -ire verbs — saying dormisco instead of dormo. The two patterns don't mix.
Misplace the stress — saying finiscòno instead of finìscono. The infix takes the stress in the loro form.

The remedy in all three cases is volume of practice. The pattern is regular and tractable; you just need to drill it until it feels automatic.

Common mistakes

❌ Noi finisciamo alle sei.

Incorrect — the -isc- infix never appears in the noi form.

✅ Noi finiamo alle sei.

Correct — noi finiamo, with no infix.

❌ Voi capiscete il problema?

Incorrect — the -isc- infix never appears in the voi form.

✅ Voi capite il problema?

Correct — voi capite, the plain -ire ending.

❌ Io dormisco bene.

Incorrect — dormire is a pure -ire verb, it doesn't take -isco.

✅ Io dormo bene.

Correct — dormo, no infix.

❌ Loro finiscòno alle sette.

Incorrect — wrong stress. In the loro form, the stress falls on the -i- of -isco-.

✅ Loro finìscono alle sette.

Correct — finìscono, with the stress on -isc-.

❌ Lei finisci ora.

Incorrect — finisci is the tu form. The lui/lei form is finisce.

✅ Lei finisce ora.

Correct — finisce in the third person singular.

Key takeaways

The -isco subgroup is the productive default for -ire verbs. Six forms, distinctive shape: -isco, -isci, -isce, -iamo, -ite, -iscono.

Three points to internalize:

The infix appears in 4 forms, not 6: io, tu, lui/lei, and loro. Noi and voi are always plain.
Sound shifts inside the conjugation: -isc- is /sk/ before -o/-ono and /ʃ/ before -i/-e. Same letters, different sound.
Stress falls on -isc- in all four infix forms: finìsco, finìsci, finìsce, finìscono. This differs from the root-stress pattern in pure -ire, -are, and -ere.

When in doubt about whether a new -ire verb is pure or -isco, default to -isco. To complete the regular system, review the pure -ire verbs, then move on to the two essential irregulars: essere and avere.

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