Aorists of Vowel-Stem Verbs | Greek Grammar

Most Greek aorists are built by adding the perfective -σα to a stem that ends in a consonant, which is why they merge into -ψα, -ξα or -σα. But a handful of everyday verbs have a present stem that ends in a vowel — ακούω ("hear"), κλαίω ("cry"), καίω ("burn"), φταίω ("be at fault"). With no visible consonant to merge into, you might expect them all to add plain -σα. Only ακούω does: κλαίω and καίω preserve a historical labial pattern, while φταίω has acquired an analogical -ξ-.

The clean type: ακούω → άκουσα

ακούω is the model of a well-behaved vowel-stem verb. The stem is ακου-, ending in the vowel sound -u-, and the aorist simply bolts -σα straight onto it: άκουσα. Nothing merges, nothing changes.

Person	Form	Reading
εγώ	άκουσα	ákusa
εσύ	άκουσες	ákuses
αυτός/-ή/-ό	άκουσε	ákuse
εμείς	ακούσαμε	akúsame
εσείς	ακούσατε	akúsate
αυτοί/-ές/-ά	άκουσαν	ákusan

The accent behaves exactly as it does in any aorist: it falls as far back as the three-syllable rule allows. In the singular and 3rd plural that is the initial ά- of the stem (άκουσα — here the stem-initial α carries it, not a separate augment), while the longer 1st/2nd-plural endings pull it one syllable forward (ακούσαμε, ακούσατε). Nothing here is special to vowel-stems — it is the ordinary recessive aorist accent.

Άκουσα κάτι να πέφτει στην κουζίνα και τρόμαξα.

ákusa káti na péfti stin kuzína ke trómaksa

I heard something fall in the kitchen and got startled.

Δεν άκουσες το ξυπνητήρι σου σήμερα το πρωί;

dhen ákuses to ksipnitíri su símera to proí;

Didn't you hear your alarm this morning?

Ακούσαμε τις ειδήσεις στο ραδιόφωνο του αυτοκινήτου.

akúsame tis idhísis sto radhiófono tu aftokinítu

We heard the news on the car radio.

The -αίω verbs: two histories, one set to learn

Now the surprise. Three common verbs end in -αίω — κλαίω (cry), καίω (burn), φταίω (be to blame) — and instead of a plain -σα they give -ψα or -ξα:

Present	→ Aorist	Meaning
κλαίω	έκλαψα	cry
καίω	έκαψα	burn
φταίω	έφταιξα	be at fault, be to blame

Why -ψα and -ξα, when there is no π/β/φ or κ/γ/χ in sight? κλαίω and καίω continue an old labial pattern: historical κλαυ- and καυ- combine with σ and surface with -ψ-, just as an ordinary labial does. φταίω has a different history. Ancient πταίω had a plain σ-aorist (ἔπταισα); Modern Greek έφταιξα acquired its -ξ- by analogy with velar aorists. The modern forms therefore rhyme, but they do not all hide the same kind of consonant. For learning purposes, memorize the three outcomes and connect only the two -ψα forms directly with the labial merge.

Το μωρό έκλαψε όλη νύχτα και δεν κλείσαμε μάτι.

to moró éklapse óli níchta ke dhen klísame máti

The baby cried all night and we didn't sleep a wink.

Έκλαψα από τη χαρά μου όταν την είδα στο αεροδρόμιο.

éklapsa apó ti chará mu ótan tin ídha sto aerodhrómio

I cried for joy when I saw her at the airport.

Πρόσεχε, έκαψα κατά λάθος το ρύζι στην κατσαρόλα.

prósiche, ékapsa katá láthos to rízi stin katsaróla

Careful, I accidentally burned the rice in the pot.

Εγώ έφταιξα για τον καβγά, το παραδέχομαι.

eghó éfteksa ya ton kavghá, to paradhéchome

I was to blame for the argument, I admit it.

Ποιος έφταιξε που χάλασε όλο το σχέδιο;

pios éftekse pu chálase ólo to schédhio;

Whose fault was it that the whole plan fell apart?

💡

For neutral Standard Greek, learn έκλαψα, έκαψα, έφταιξα as a small set. The first two reflect a historical labial; the ξ in έφταιξα is analogical. Older Greek does attest έφταισα, so it is not linguistic nonsense, but it is not the neutral modern form taught here.

The suppletive vowel-stems belong to another page

Two of the most frequent vowel-final verbs of all — λέω (say) and τρώω (eat), together with πάω (go) — also end in a vowel, but they do not merge anything: they switch to a completely different root. λέω → είπα, τρώω → έφαγα, πάω → πήγα. These are pure suppletion, not vowel-stem merging, so they live with the irregular and suppletive aorists. It is worth keeping the two ideas apart: άκουσα / έκλαψα are regular outcomes of a vowel (or hidden-consonant) stem, while είπα / έφαγα are root swaps you memorise wholesale.

Είπα καληνύχτα σε όλους και πήγα για ύπνο.

ípa kaliníchta se ólus ke pígha ya ípno

I said goodnight to everyone and went to bed.

Common Mistakes

1. Regularizing κλαίω to a plain -σα. The hidden labial makes it -ψα.

❌ Το παιδί έκλαισε γιατί έχασε το παιχνίδι του.

Incorrect — κλαίω hides a labial: the aorist is έκλαψε.

✅ Το παιδί έκλαψε γιατί έχασε το παιχνίδι του.

to pedhí éklapse yatí échase to pechnídhi tu

The child cried because it lost its toy.

2. Treating φταίω as if it hid a velar. The modern -ξ- is analogical, not the trace of a buried κ/γ/χ. Neutral Standard Greek nevertheless uses έφταιξα.

✅ Δεν έφταιξα εγώ που αργήσαμε τόσο πολύ.

dhen éfteksa eghó pu aryísame tóso polí

It wasn't my fault that we were so late.

3. Adding a merge consonant to ακούω. A true vowel-stem takes a plain -σα, with no ξ or ψ.

❌ Άκουξα ότι παντρεύεται τον άλλο μήνα.

Incorrect — ακούω is a clean vowel-stem: the aorist is άκουσα.

✅ Άκουσα ότι παντρεύεται τον άλλο μήνα.

ákusa óti pandrévete ton álo mína

I heard she's getting married next month.

4. Not shifting the accent to the stem in the plural. As in every aorist, the long ending pulls it forward: ακούσαμε.

❌ Άκουσαμε τη μουσική από το διπλανό διαμέρισμα.

Incorrect — the 1st plural moves the accent forward: ακούσαμε.

✅ Ακούσαμε τη μουσική από το διπλανό διαμέρισμα.

akúsame ti musikí apó to dhiplanó dhiamérizma

We heard the music from the flat next door.

Key Takeaways

Vowel-stem verbs add the perfective -σα with no consonant to merge — the clean case is ακούω → άκουσα.
In the -αίω set, κλαίω → έκλαψα and καίω → έκαψα reflect a historical labial pattern; φταίω → έφταιξα has analogical -ξ-. These are the neutral Standard forms.
The accent follows the normal aorist pattern: άκουσα in the singular, ακούσαμε in the 1st/2nd plural.
Keep these apart from the suppletive vowel-finals λέω → είπα, τρώω → έφαγα, πάω → πήγα, which switch root entirely — see the irregular and suppletive aorists.
All four verbs — hear, cry, burn, be-at-fault — are everyday vocabulary, so their aorists earn their keep fast.

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