"Irregular verbs" sounds like a warning that a whole verb is unpredictable. In Greek it is much narrower than that, and the narrowness is the good news: irregularity is concentrated almost entirely in one half of the verb — the perfective stem. The present tense of an irregular Greek verb is, in the overwhelming majority of cases, as regular as any verb in the book. This page maps the field so you know what you are actually up against, and routes you to the page that handles each shape.
The present is the safe half
Take βλέπω, the poster child for Greek irregularity. Its present conjugates exactly like γράφω — βλέπω, βλέπεις, βλέπει, βλέπουμε, βλέπετε, βλέπουν — and its imperfect is the equally tame έβλεπα. Nothing anywhere in that half of the verb hints at trouble. The trouble is on the other side: the perfective stem is δ-, giving είδα, θα δω, να δω, δες. Same verb, two utterly different halves.
Βλέπω τηλεόραση μόνο όταν είμαι πολύ κουρασμένος.
vlépo tileórasi móno ótan íme polí kurazménos
I only watch TV when I'm really tired.
Χθες όμως είδα τρία επεισόδια το ένα μετά το άλλο.
chthes ómos ídha tría episódhia to éna metá to álo
Yesterday, though, I watched three episodes back to back.
That is the pattern for nearly the whole irregular class: μπαίνω, στέλνω, δίνω, μένω, φεύγω, μαθαίνω, παίρνω all have perfectly ordinary presents and a perfective stem that no rule will hand you.
The honest exception. A short list of verbs is irregular in the present too — the ones whose stem ends in a vowel and contracts: λέω (λες, λέει, λέμε, λέτε, λένε), τρώω (τρως, τρώμε), πάω (πας, πάμε), ακούω (ακούς), plus κλαίω, καίω and φταίω (κλαις, καις, φταις). And είμαι is irregular from end to end. Those are real, and they get their own treatment on vowel-final stems. Outside that handful, if a Greek verb looks normal in the present, its present is normal.
What "learning an irregular verb" actually costs you
For a regular verb you memorise one thing beyond the headword: the perfective stem. γράψ- then gives έγραψα, θα γράψω, να γράψω, γράψε, έχω γράψει — the whole other half of the verb, from one item.
Irregular verbs charge you a second item, because the aorist and the bare perfective can drift apart:
- βλέπω: aorist είδα, but dependent δω
- έρχομαι: aorist ήρθα, but dependent έρθω
- πάω: aorist πήγα, but dependent πάω
- πίνω: aorist ήπια, but dependent πιω
Knowing είδα does not let you predict δω, and knowing δω does not let you predict είδα. So the practical rule is: record an irregular verb as three forms — present, aorist 1sg, dependent 1sg. That trio generates the rest of the verb. Everything else on this page is a way of making that trio easier to remember.
The five shapes
Almost every irregular verb in the language falls into one of these. Each has its own page; this table is the map.
| Type | What happens | Examples (present → dependent / aorist) |
|---|---|---|
| Suppletive stems | The perfective comes from a different root entirely | βλέπω → δω / είδα · λέω → πω / είπα · τρώω → φάω / έφαγα |
| Vowel-final stems | The stem ends in a vowel, so the present contracts; the perfective may follow the -σ- rule (ακούω) or not (καίω) | ακούω → ακούσω / άκουσα · κλαίω → κλάψω / έκλαψα · καίω → κάψω / έκαψα |
| Nasal stems | The -ν- or -αιν- is imperfective-only scaffolding and drops, leaving the root untouched | μπαίνω → μπω / μπήκα · μαθαίνω → μάθω / έμαθα · καταλαβαίνω → καταλάβω / κατάλαβα |
| Stem alternation | Same root, different vowel in the perfective | στέλνω → στείλω / έστειλα · φεύγω → φύγω / έφυγα · μένω → μείνω / έμεινα |
| Class Β oddities | Ending-stressed verbs that skip the expected -ησ- | ξεχνάω → ξεχάσω / ξέχασα · γελάω → γελάσω / γέλασα · μπορώ → μπορέσω / μπόρεσα |
Two examples of the middle types in the wild — note how ordinary the presents of these verbs are, and how far the perfectives travel:
Μπήκα στο γραφείο και κατάλαβα αμέσως ότι κάτι είχε συμβεί.
bíka sto ghrafío ke katálava amésos óti káti íche simví
I walked into the office and knew at once that something had happened.
Σου έστειλα δύο μηνύματα χθες, δεν τα είδες;
su éstila dhío minímata chthes, dhen ta ídhes;
I sent you two messages yesterday — didn't you see them?
Δεν μπόρεσα να έρθω γιατί ξέχασα τελείως το ραντεβού.
dhen bóresa na értho yatí kséchasa telíos to randevú
I couldn't come because I completely forgot about the appointment.
Alongside the five sits a sixth group that is irregular in a different sense: the impersonals — πρέπει, αρέσει, χρειάζεται, πρόκειται — which are missing most of their persons rather than most of their stems. They live on impersonal verbs. And the deponents (έρχομαι, κάθομαι, θυμάμαι) are irregular in voice — their present wears mediopassive endings while meaning something entirely active; they are handled on deponent verbs.
Three verbs with no perfective stem at all
If irregularity lives in the perfective stem, the most irregular verbs of all should be the ones that never grew one. Greek has exactly that: είμαι, έχω and ξέρω have a single stem, and it does all the work. (A few rarer verbs — ανήκω "belong", αξίζω "be worth" — are defective in the same way; these three are the ones you meet daily.)
| Verb | Present | Past | Future | After να |
|---|---|---|---|---|
| είμαι (be) | είμαι | ήμουν | θα είμαι | να είμαι |
| έχω (have) | έχω | είχα | θα έχω | να έχω |
| ξέρω (know) | ξέρω | ήξερα | θα ξέρω | να ξέρω |
Read the table sideways and you see the consequence: the future and the να-form are identical to the present, because there is no second stem to switch to. And the past column is an imperfect — ήμουν, είχα, ήξερα all mean "was / had / knew" as a state, and there is no separate aorist behind them.
Θα έχω τελειώσει μέχρι τις έξι, μην ανησυχείς.
tha écho teliósi méchri tis éksi, min anisichís
I'll have finished by six, don't worry.
Δεν είχα ιδέα ότι ήσουν κι εσύ εκεί χθες.
dhen ícha idhéa óti ísun ki esí ekí chthes
I had no idea you were there too yesterday.
When Greek genuinely needs a bounded, one-off event from these meanings, it changes verb rather than changing stem: "I found out" is έμαθα, "I got to know (someone)" is γνώρισα, "I acquired" is απέκτησα.
Δεν το ήξερα καθόλου — πότε το έμαθες εσύ;
dhen to íksera kathólu — póte to émathes esí;
I had no idea — when did you find out?
The same irregular root turns up in the passive
Here is the return on your investment. The passive aorist is built on the perfective root as well, so the odd stem you learned for the active pays a second time:
- δίνω → δόθηκε ("was given"), not a form built on δίν-
- βρίσκω → βρέθηκε ("was found")
- παίρνω → πάρθηκε ("was taken")
- λέω → ειπώθηκε ("was said")
Το πορτοφόλι μου βρέθηκε τελικά κάτω από το κάθισμα.
to portofóli mu vréthike teliká káto apó to káthizma
My wallet turned up under the seat in the end.
Τα κλειδιά δόθηκαν στον καινούριο ένοικο την Παρασκευή.
ta klidhiá dhóthikan ston kenúrio éniko tin Paraskeví
The keys were handed over to the new tenant on Friday.
Nothing new joins the club
Greek irregularity is a closed, ancient set. It is not a productive process, and no verb entering the language today joins it. The loan verbs in -άρω — παρκάρω, σκανάρω, ποστάρω, σερφάρω — are all straightforwardly regular, with aorists πάρκαρα, σκάναρα, πόσταρα (many speakers also say παρκάρισα, σκανάρισα; both are current). Whatever else happens to Greek, the irregular list you learn now will not grow.
Πάρκαρα μπροστά στο φαρμακείο και ανέβηκα ένα λεπτό.
párkara brostá sto farmakío ke anévika éna leptó
I parked in front of the pharmacy and ran up for a minute.
Common Mistakes
1. Manufacturing a perfective for έχω. The -σ- rule builds perfective stems for verbs that have one. έχω does not, so there is nothing for the rule to operate on.
❌ Θα έξω λίγο χρόνο το Σάββατο το πρωί.
Incorrect — έχω has no perfective stem, so the future keeps the same form: Θα έχω.
✅ Θα έχω λίγο χρόνο το Σάββατο το πρωί.
tha écho lígho chróno to Sávato to proí
I'll have a bit of time on Saturday morning.
2. Building the passive aorist on the present stem. The -θηκα endings attach to the perfective root, so an irregular verb stays irregular in the passive.
❌ Η απόφαση παίρθηκε χωρίς εμάς.
Incorrect — the passive aorist uses the perfective root πάρ-, not the present stem παίρν-: πάρθηκε.
✅ Η απόφαση πάρθηκε χωρίς εμάς.
i apófasi párthike chorís emás
The decision was taken without us.
3. Giving ξέρω the default έ- augment. Most Class Α verbs take έ- in the past (έγραφα, έπαιζα), but ξέρω takes ή-, like θέλω → ήθελα.
❌ Έξερα από την αρχή ότι κάτι δεν πήγαινε καλά.
Incorrect — the past of ξέρω is ήξερα, with the η- augment.
✅ Ήξερα από την αρχή ότι κάτι δεν πήγαινε καλά.
íksera apó tin archí óti káti dhen píyene kalá
I knew from the start that something was off.
4. Keeping the -αιν- of the present in the perfective. In the nasal group that syllable is imperfective-only scaffolding (it is there in καταλαβαίνω and καταλάβαινα alike); the perfective stem is the shorter root underneath.
❌ Δεν καταλαβαίνησα τι μου είπε στο τηλέφωνο.
Incorrect — the perfective stem of καταλαβαίνω is καταλάβ-: δεν κατάλαβα.
✅ Δεν κατάλαβα τι μου είπε στο τηλέφωνο.
dhen katálava ti mu ípe sto tiléfono
I didn't catch what he said to me on the phone.
Key Takeaways
- Greek irregularity is concentrated in the perfective stem. For nearly every irregular verb the present and imperfect are completely regular — βλέπω, έβλεπα are ordinary; είδα, δω are not.
- The honest exception is the small vowel-final group (λέω, τρώω, πάω, ακούω, κλαίω, καίω, φταίω), which also contracts in the present, plus είμαι, which is irregular throughout.
- Because the aorist and the dependent can diverge (είδα vs δω, ήρθα vs έρθω), record an irregular verb as present + aorist 1sg + dependent 1sg — three items, not two.
- The five shapes are suppletive stems, vowel-final stems, nasal stems, stem alternation and Class Β oddities; impersonals and deponents are irregular in person and voice rather than in stem.
- είμαι, έχω, ξέρω have only one stem, so their future and να-form look exactly like their present, and their past is an imperfect (ήμουν, είχα, ήξερα).
- The irregular perfective root also builds the passive aorist (δόθηκε, βρέθηκε, πάρθηκε), so learning it pays twice.
- The class is closed: new verbs, including the -άρω loans, are regular.
Now practice Greek
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Start learning Greek →Related Topics
- Suppletive Verbs (βλέπω→είδα)B1 — Six everyday verbs — βλέπω, λέω, τρώω, πάω, έρχομαι, παίρνω — carry two roots each, one for the present and a completely different one for everything perfective. This page puts each verb's present, aorist, να-form, command and perfect on a single card, shows which cells you actually have to memorise and which fall out of the others, and marks the two verbs where the chain breaks.
- Nasal-Stem Verbs (μπαίνω, πίνω)B1 — In μαθαίνω, καταλαβαίνω, μπαίνω, πίνω and δίνω the -ν- or -αιν- belongs to the imperfective half of the verb only — it is there in μαθαίνω and μάθαινα alike, and gone from everything perfective. Drop it and the bare root underneath is the perfective stem (μάθ-, καταλάβ-, μπ-, πι-). Covers the whole family, the -ηκα aorists that look passive and are not, the causative partners in -άζω, and μαθαίνω's double life as both 'learn' and 'teach'.
- Stem-Alternation Verbs (στέλνω→έστειλα)B2 — In στέλνω → έστειλα → στάλθηκε the root vowel itself is doing the grammar: ε in the present, ει in the perfective, α in the passive. This page works through the whole alternating set — στέλνω, πλένω, σπέρνω, δέρνω, μένω, φεύγω, πεθαίνω, φέρνω — with their dependents, commands and participles, and explains why these dependents (στείλω, πλύνω, μείνω) are more dangerous than δω or πω.
- Vowel-Final Stems (ακούω, τρώω, λέω)B1 — Seven everyday verbs — λέω, τρώω, ακούω, πάω, κλαίω, καίω, φταίω — end their stem in a vowel, and that one fact reshapes the whole verb: a present with no ending vowel (λες, τρως, ακούς), a γ that reappears the moment you leave the present (έλεγα, άκουγα, κλαίγοντας, ακούγεται), and three different kinds of aorist inside one small class.
- Irregular Perfective StemsB1 — The commonest Greek verbs — see, say, eat, go, take, find, give, drink, come in, go out — build their perfective stem suppletively, swapping in a whole new form (βλέπω → δω, λέω → πω, τρώω → φάω) instead of adding -σ-. There is no rule; because these are the highest-frequency verbs, memorising the twelve or so pairs is one of the best-value things you can do in Greek.
- Irregular and Suppletive AoristsB1 — The dozen aorists you cannot derive and must simply know — είδα, είπα, ήρθα, ήπια, πήγα, βρήκα, μπήκα, βγήκα, πήρα, έφαγα, έδωσα, έμεινα — grouped by their shared shape, and precisely because they belong to Greek's most frequent verbs, the highest-value forms in the whole past tense.