Building the Perfective Stem | Greek Grammar

Once you accept that aspect forces a choice, the practical question is: how do you actually make the perfective form? Greek keeps two stems per verb — the imperfective one is just the present stem you already know (γράφ-, αγαπ-), and the perfective one is built from it by a single, learnable operation. Get the perfective stem and you get four things at once: the aorist (έγραψα), the simple future (θα γράψω), the perfective subjunctive (να γράψω) and the perfective imperative (γράψε). This page is the assembly rule.

The core operation: add -σ-

Every regular Greek verb builds its perfective stem by adding -σ- (sigma) to the present stem. Everything that looks complicated is just a side-effect of two questions:

Does a linking vowel go in first? — the line between the two conjugation classes.
What happens where the -σ- lands on a consonant? — the merges, handled on their own page.

Answer those and the whole system falls out.

Class Α: stem + -σ-

Class Α verbs — the ones stressed on the stem (λύνω, γράφω, ακούω) — add the -σ- straight onto the stem, no vowel in between.

Where the stem ends in a vowel (or a nasal -ν- that simply drops), the join is clean:

Present	Perfective stem	Aorist (1sg)	Meaning
λύνω	λύσ-	έλυσα	untie, solve
ακούω	ακούσ-	άκουσα	hear
κλείνω	κλείσ-	έκλεισα	close

Δώσε μου ένα λεπτό να λύσω αυτό το πρόβλημα και έρχομαι.

dhóse mu éna leptó na líso aftó to próvlima ke érchome

Give me a minute to solve this problem and I'll come. (perfective subjunctive on λύσ-)

Θα ακούσω το τραγούδι σου μόλις γυρίσω σπίτι.

tha akúso to traghúdhi su mólis yiríso spíti

I'll listen to your song as soon as I get home. (simple future on ακούσ-)

Where the stem ends in a consonant, the -σ- fuses with it into ψ, ξ or σ (γράφ- → γράψ-, τρέχ- → τρέξ-, διαβάζ- → διάβασ-). Those merges are the whole subject of perfective consonant changes — this page sends you there and moves on.

The -εύω sub-family: -εψ-

A large, tidy pocket of Class Α is the verbs in -εύω. The historical labial in that ending surfaces before the -σ- as -εψ-:

Present	Perfective stem	Aorist (1sg)	Meaning
δουλεύω	δουλέψ-	δούλεψα	work
χορεύω	χορέψ-	χόρεψα	dance
ταξιδεύω	ταξιδέψ-	ταξίδεψα	travel
μαγειρεύω	μαγειρέψ-	μαγείρεψα	cook

Δούλεψα όλη μέρα και δεν πρόλαβα ούτε να φάω.

dhúlepsa óli méra ke dhen prólava úte na fáo

I worked all day and didn't even get to eat.

Χόρεψα μέχρι το πρωί στο γλέντι του χωριού.

chórepsa méchri to proí sto ghléndi tu choriú

I danced until morning at the village feast.

Αν έρθεις το Σάββατο, θα σου μαγειρέψω μουσακά.

an érthis to Sávato, tha su mayirépso musaká

If you come on Saturday, I'll cook you moussaka.

Class Β: linking vowel + -σ-

Class Β verbs — stressed on the ending (αγαπώ, μιλώ, μπορώ) — have a bare stem with no final consonant to add to, so they slot a linking vowel in before the -σ-. The vowel comes in three flavours, and which one a verb takes is a lexical fact you learn with the verb.

The -ήσ- family (the default, and by far the largest)

Most Class Β verbs take -ησ-. When in doubt, this is the safe bet:

Present	Perfective stem	Aorist (1sg)	Meaning
αγαπώ	αγαπήσ-	αγάπησα	love
μιλώ	μιλήσ-	μίλησα	speak
ρωτώ	ρωτήσ-	ρώτησα	ask
κρατώ	κρατήσ-	κράτησα	hold, keep
οδηγώ	οδηγήσ-	οδήγησα	drive

Τον αγάπησα από την πρώτη κιόλας στιγμή.

ton aghápisa apó tin próti kyólas stighmí

I loved him from the very first moment.

Πρέπει να μιλήσω με τον γιατρό πριν αποφασίσω.

prépi na milíso me ton yatró prin apofasíso

I need to speak to the doctor before I decide.

Τον ρώτησα την ώρα και μου την είπε ευγενικά.

ton rótisa tin óra ke mu tin ípe evyeniká

I asked him the time and he told me politely.

The -ασ- family

A smaller group takes -ασ-:

Present	Perfective stem	Aorist (1sg)	Meaning
γελώ	γελάσ-	γέλασα	laugh
διψώ	διψάσ-	δίψασα	be thirsty
πεινώ	πεινάσ-	πείνασα	be hungry
χαλώ	χαλάσ-	χάλασα	break, ruin

Γέλασα τόσο πολύ που πόνεσε η κοιλιά μου.

yélasa tóso polí pu pónese i kiliá mu

I laughed so hard my belly hurt.

The -εσ- family

A third, still smaller group takes -εσ- — and it includes two verbs you meet on day one, μπορώ and φορώ:

Present	Perfective stem	Aorist (1sg)	Meaning
μπορώ	μπορέσ-	μπόρεσα	can, be able
φορώ	φορέσ-	φόρεσα	wear, put on
καλώ	καλέσ-	κάλεσα	call, invite

Δεν μπόρεσα να κοιμηθώ καθόλου χθες το βράδυ.

dhen bóresa na kimithó kathólu chthes to vrádhi

I couldn't sleep at all last night.

Φόρεσα το καλό μου κοστούμι για τον γάμο.

fóresa to kaló mu kostúmi ya ton ghámo

I put on my good suit for the wedding.

💡

There is no rule that tells you from the present alone whether a Class Β verb takes -ησ-, -ασ- or -εσ-. Treat -ησ- as the default and learn the -ασ- and -εσ- verbs as a short memorised list — the everyday -ασ- ones (γελάω, διψάω, πεινάω, χαλάω, κρεμάω, γερνάω) and the everyday -εσ- ones (μπορώ, φορώ, πονώ, καλώ) cover almost all of them. Store each verb as a pair, e.g. μπορώ → μπόρεσα, the same way you'd store an English irregular past.

Why this one stem is worth the trouble

The perfective stem is not just for the past. Build it once and it powers four different forms — you only change what leans on it:

Form	Recipe	Example (μιλήσ-)
Aorist	augment + stem + past endings	μίλησα — I spoke
Simple future	θα + stem + present endings	θα μιλήσω — I'll speak (once)
Perfective subjunctive	να + stem + present endings	να μιλήσω — to speak (once)
Perfective imperative	stem + imperative ending	μίλησε — speak!

Θέλω να σου μιλήσω, να με πάρεις όταν μπορέσεις.

thélo na su milíso, na me páris ótan borésis

I want to talk to you — call me when you can. (perfective να on two stems)

The aorist endings that attach here are the subject of Aorist: Class Α; the futures and subjunctives that reuse the stem are covered in their own sections. What matters on this page is that they all draw from the one stem you just built.

Common Mistakes

1. Building a Class Β perfective without the linking vowel. μιλώ cannot go straight to ×μιλσω; the vowel is obligatory.

❌ Πρέπει να σε ρωτσω κάτι σημαντικό.

Incorrect — ρωτάω is Class Β and needs a linking vowel: ρωτήσω.

✅ Πρέπει να σε ρωτήσω κάτι σημαντικό.

prépi na se rotíso káti simandikó

I need to ask you something important.

2. Using -ασ- (or -εσ-) where the verb wants -ησ-, or vice versa. αγαπώ takes -ησ-, not ×αγαπάσω; μπορώ takes -εσ-, not ×μπορήσω.

❌ Δεν μπόρησα να έρθω στο πάρτι σου.

Incorrect — μπορώ takes -εσ-: μπόρεσα.

✅ Δεν μπόρεσα να έρθω στο πάρτι σου.

dhen bóresa na értho sto párti su

I couldn't come to your party.

3. Treating an -εύω verb like a Class Β verb. δουλεύω is Class Α; its perfective is δούλεψ-, not ×δουλεύησα.

❌ Δουλεύησα δέκα χρόνια σε εκείνη την εταιρεία.

Incorrect — -εύω gives -εψ-: δούλεψα.

✅ Δούλεψα δέκα χρόνια σε εκείνη την εταιρεία.

dhúlepsa dhéka chrónia se ekíni tin etería

I worked ten years at that company.

4. Leaving the -σ- off a vowel-final Class Α verb. A clean vowel join is still a join: for a one-off future ακούω needs the perfective ακούσω (θα ακούσω), not the bare present stem.

❌ Αύριο θα ακούω τι έχει να μου πει και θα αποφασίσω.

Incorrect for a one-off — the simple future needs the perfective ακούσω.

✅ Αύριο θα ακούσω τι έχει να μου πει και θα αποφασίσω.

ávrio tha akúso ti échi na mu pi ke tha apofasíso

Tomorrow I'll hear what he has to say to me and I'll decide.

Key Takeaways

The perfective stem = present stem -σ-
. Everything else is a detail of how the -σ- attaches.
Class Α adds -σ- directly to the stem (λύσ-, ακούσ-); the -εύω sub-family gives -εψ- (δουλέψ-, χορέψ-); consonant-final stems merge — see the consonant-changes page.
Class Β inserts a linking vowel: -ησ- (the default: αγαπήσ-, μιλήσ-), -ασ- (γελάσ-, διψάσ-), or -εσ- (μπορέσ-, φορέσ-). The vowel is unpredictable — learn it per verb.
This one stem feeds the aorist, simple future, perfective subjunctive and perfective imperative — build it once, use it four ways.

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