Nasal-Stem Verbs (μπαίνω, πίνω) | Greek Grammar

A large slice of the Greek "irregular" list is not really irregular at all — it is one tidy fact repeated across two dozen verbs. In μαθαίνω, καταλαβαίνω, μπαίνω, πίνω and their kin, the -ν- or -αιν- you see in the present is scaffolding that belongs to the imperfective side of the verb only. Take it away and what is left — μάθ-, καταλάβ-, μπ-, πι- — is the perfective stem, ready to build the aorist, the θα/να form and the command. Once you can see the scaffolding, these verbs stop being memorisation and become subtraction.

The test: what does the -αιν- leave behind?

Greek has two families whose present tense is padded out this way, and the overview sorts them with a single question: when the padding drops, is the root untouched?

Untouched → this page. μαθαίνω → έμαθα (μαθ- is still μαθ-), καταλαβαίνω → κατάλαβα, μπαίνω → μπήκα.
The root's own vowel changes → stem alternation. στέλνω → έστειλα (στελν- becomes στειλ-), πεθαίνω → πέθανα, πλένω → έπλυνα.

The two families look identical in the present — both end in -νω — and part company only in the aorist. That is why the aorist is the diagnostic form: it is the first place the root shows its real shape.

The -αίνω verbs whose root survives

Present	Meaning	After θα / να	Aorist	Command (sg)
μαθαίνω	learn; find out; teach	μάθω	έμαθα	μάθε
παθαίνω	suffer, undergo	πάθω	έπαθα	—
καταλαβαίνω	understand	καταλάβω	κατάλαβα	κατάλαβε
τυχαίνω	happen to, chance	τύχω	έτυχα	—
χορταίνω	have had enough (food)	χορτάσω	χόρτασα	χόρτασε
ζεσταίνω	heat, warm up	ζεστάνω	ζέστανα	ζέστανε
αρρωσταίνω	fall ill	αρρωστήσω	αρρώστησα	—

The first four throw the -αιν- away and add nothing at all: μαθ- + α = έμαθα. The last three keep their root just as faithfully but still take an ordinary perfective suffix on top (χορτ-ασ-α, ζεστ-αν-α, αρρωστ-ησ-α) — the root survives, which is what puts them on this page, but they are not suffix-free. Watch ζέστανα in particular: on the surface it is the same shape as πέθανα, which is on the other page. The difference is where the α comes from — ζεστ- is an intact root (compare ζεστός, ζέστη) with an -αν- suffix bolted on, whereas in πεθαίνω the α is the root vowel (θαν-, as in θάνατος) alternating with the αι of θαιν-.

Έμαθα να οδηγώ πολύ αργά, στα τριάντα μου.

ématha na odhighó polí arghá, sta triánda mu

I learned to drive very late, in my thirties.

Δεν κατάλαβα λέξη από όσα είπε ο δικηγόρος.

dhen katálava léksi apó ósa ípe o dhikighóros

I didn't understand a word of what the lawyer said.

Τι έπαθες στο χέρι σου; Πονάει;

ti épathes sto chéri su; ponái;

What happened to your hand? Does it hurt?

Note the front vowel in έμαθα and έπαθα: it is an ordinary augment, there only to host the stress, so it drops the moment the word grows — έμαθα, έμαθες, έμαθε but μάθαμε, μάθατε. κατάλαβα needs none at all: at four syllables the stress already has an antepenult to sit on (κα-τά-λα-βα).

Μάθαμε τα νέα από τη γειτόνισσα, όχι από εσάς.

máthame ta néa apó ti yitónisa, óchi apó esás

We heard the news from the neighbour, not from you.

The four motion verbs: μπαίνω, βγαίνω, ανεβαίνω, κατεβαίνω

In, out, up, down — four verbs you use every hour, and they share one shape from top to bottom.

Present	Meaning	After θα / να	Aorist	Command sg / pl
μπαίνω	go in, get in	μπω	μπήκα	μπες / μπείτε
βγαίνω	go out, come out	βγω	βγήκα	βγες / βγείτε
ανεβαίνω	go up, climb	ανέβω	ανέβηκα	ανέβα / ανεβείτε
κατεβαίνω	go down, get off	κατέβω	κατέβηκα	κατέβα / κατεβείτε

Two things are worth naming out loud. First, the commands split: the two short verbs take -ες (μπες, βγες), the two compounds take a bare -α (ανέβα, κατέβα), and no rule predicts that — the whole irregular command set is drilled on irregular imperatives. Second, and more useful: μπήκα, βγήκα, ανέβηκα and κατέβηκα wear the ending -ηκα, which is also the passive aorist ending (πλύθηκα "I was washed", γράφτηκα "I was enrolled"). These four are not passive in any sense — μπήκα means I went in, an act you performed. The ending is a historical coincidence, and reading it as a passive is a trap laid specifically for learners who have already met -θηκα.

Μπήκαμε στο θέατρο την ώρα που έσβηναν τα φώτα.

bíkame sto théatro tin óra pu ézvinan ta fóta

We got into the theatre just as the lights were going down.

Ανέβηκα με τις σκάλες γιατί το ασανσέρ ήταν χαλασμένο.

anévika me tis skáles yatí to asansér ítan chalazméno

I walked up because the lift was broken.

Δεν μου βγαίνει ο λογαριασμός με αυτά τα νούμερα.

dhen mu vyéni o loghariazmós me aftá ta númera

The numbers don't add up for me.

That last one is a reminder that these verbs travel far beyond motion: βγαίνω covers coming out, going out for the evening, a book being published and a sum working out; μπαίνω covers getting in, fitting, and understanding (μπήκα στο νόημα, "I got the point"). Their idiom clusters are on μπαίνω and βγαίνω.

The plain -ν- verbs: πίνω and δίνω

Two very high-frequency verbs pad the present with a bare -ν- rather than a whole -αιν-.

πίνω → πιω / ήπια. Textbook case: strip the -ν- and the root πι- is exactly what the perfective uses.
δίνω → δώσω / έδωσα. Here the -ν- goes as expected, but the root vowel also shifts ι → ω, so δίνω has one foot on this page and one on stem alternation. Treat it as the family's awkward member rather than as a counterexample.

Ήπια τον καφέ μου όρθιος και έτρεξα για το τρένο.

ípia ton kafé mu órthios ke étreksa ya to tréno

I drank my coffee standing up and ran for the train.

Δώσε μου δύο λεπτά να τελειώσω και είμαι μαζί σου.

dhóse mu dhío leptá na telióso ke íme mazí su

Give me two minutes to finish and I'm all yours.

The same -ν- sits in a crowd of verbs nobody calls irregular, and it behaves identically there: φτάνω → έφτασα, χάνω → έχασα, πιάνω → έπιασα, κλείνω → έκλεισα. The -ν- drops, the root takes the ordinary -σ- of the perfective stem, and nothing surprises anyone. μαθαίνω and μπαίνω are doing the same thing; they just have nothing left to attach the -σ- to.

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When a Greek verb ends in -αίνω or -νω, your first move should be to delete the nasal and look at what remains. If it is a pronounceable root — μαθ-, πάθ-, καταλάβ-, πι-, φτά- — you have found the perfective stem and the aorist is one augment away. The -αιν- belongs to the imperfective half of the verb (it is there in μάθαινα too), not to the word itself.

Every one of them has a causative twin in -άζω

This family is intransitive: you go in, you come out, you go up. When something is made to go in or out or up, Greek does not add a prefix or change the voice — it reaches for a different verb, and the pairs are worth learning as pairs. (ανεβαίνω and κατεβαίνω do take a bare accusative in ανεβαίνω τις σκάλες, "I go up the stairs" — but that is the route travelled, not a thing being moved, and it does not make them causative.)

Intransitive (this page)	Causative	Contrast
μπαίνω — go in	βάζω — put in	Μπήκα στο αυτοκίνητο / Έβαλα τις τσάντες στο αυτοκίνητο
βγαίνω — come out	βγάζω — take out	Βγήκα έξω / Έβγαλα τον σκύλο έξω
ανεβαίνω — go up	ανεβάζω — take up, upload	Ανέβηκα πάνω / Ανέβασα τις βαλίτσες πάνω
κατεβαίνω — go down	κατεβάζω — bring down, download	Κατέβηκα κάτω / Κατέβασα το αρχείο

English uses one verb for both jobs (the price went up / they put the price up), so this is a genuine extra choice for an English speaker. The wider pattern — why Greek splits some verbs into two and lets others do both jobs — is on active/passive verb pairs.

Ανέβασε τις βαλίτσες πάνω και κατέβηκε αμέσως.

anévase tis valítses páno ke katévike amésos

He took the suitcases upstairs and came straight back down.

μαθαίνω does two jobs at once

One member of the family deserves a paragraph of its own. μαθαίνω means learn, find out — and also teach. There is no separate everyday verb for teaching outside a classroom (διδάσκω is what a teacher does professionally), so the same verb serves both directions, and what tells them apart is whether there is a person in the genitive: Έμαθα = I learned; Του έμαθα = I taught him.

Ο παππούς μου έμαθε να ψαρεύω όταν ήμουν οκτώ.

o papús mu émathe na psarévo ótan ímun októ

My grandfather taught me to fish when I was eight.

Έτυχε να είμαστε στην ίδια πτήση και δεν το ξέραμε.

étiche na ímaste stin ídhia ptísi ke dhen to ksérame

We happened to be on the same flight and had no idea.

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The third useful sense of μαθαίνω is "find out, hear", and it is the standard filler for the gap in ξέρω, which has no aorist of its own: Δεν το ήξερα — πότε το έμαθες; When English switches from know to found out, Greek switches from ξέρω to έμαθα.

Common Mistakes

1. Giving μπαίνω a direct object. English enter the room takes an object; Greek μπαίνω is a verb of motion and needs σε.

❌ Μπήκαμε την αίθουσα πέντε λεπτά αργότερα.

Incorrect — μπαίνω takes σε + accusative: μπήκαμε στην αίθουσα.

✅ Μπήκαμε στην αίθουσα πέντε λεπτά αργότερα.

bíkame stin éthusa pénde leptá arghótera

We went into the hall five minutes late.

2. Using the intransitive verb where the causative twin is meant. βγήκα says I came out; taking something out is βγάζω.

❌ Βγήκα τα σκουπίδια πριν κοιμηθώ.

Incorrect — βγαίνω is intransitive; taking something out is the causative έβγαλα.

✅ Έβγαλα τα σκουπίδια πριν κοιμηθώ.

évghala ta skupídhia prin kimithó

I took the rubbish out before going to bed.

3. Spelling the -αι- of the present as ε. μπαίνω, βγαίνω and μαθαίνω sound as though they had an ε and are written with αι.

❌ Μπένω στο μετρό στο Σύνταγμα.

Incorrect — the present is spelled μπαίνω, with αι.

✅ Μπαίνω στο μετρό στο Σύνταγμα και κατεβαίνω στο Μοναστηράκι.

béno sto metró sto Síndaghma ke katevéno sto Monastiráki

I get on the metro at Syntagma and get off at Monastiraki.

4. Building a regular -ησα aorist on the full present stem. The -αιν- has to go first, and what is left needs no suffix.

❌ Μάθησα ελληνικά στο πανεπιστήμιο.

Incorrect — the aorist of μαθαίνω is έμαθα, built on the bare root μαθ-.

✅ Έμαθα ελληνικά στο πανεπιστήμιο, αλλά τα ξέχασα σχεδόν όλα.

ématha eliniká sto panepistímio, alá ta kséchasa schedhón óla

I learned Greek at university, but I've forgotten nearly all of it.

Key Takeaways

The -ν- / -αιν- is imperfective scaffolding — present and imperfect alike (μαθαίνω, μάθαινα), gone from everything perfective. Remove it and the root underneath is the perfective stem: μαθ-, πάθ-, καταλάβ-, μπ-, βγ-, πι-.
This page holds the verbs whose root survives intact; verbs whose root vowel changes (στέλνω → έστειλα, πεθαίνω → πέθανα) are on stem alternation.
The four motion verbs share one shape: μπω/μπήκα, βγω/βγήκα, ανέβω/ανέβηκα, κατέβω/κατέβηκα — but their commands split into μπες, βγες against ανέβα, κατέβα.
Those -ηκα aorists are active, despite wearing the ending of the passive aorist. μπήκα is I went in, never "I was gone into".
πίνω → πιω is the clean case of a bare -ν-; δίνω → δώσω drops its -ν- but also recolours the root vowel, which makes it the family's awkward member.
Each of these intransitives has a causative twin in -άζω: μπαίνω/βάζω, βγαίνω/βγάζω, ανεβαίνω/ανεβάζω, κατεβαίνω/κατεβάζω.
μαθαίνω means learn, find out and teach; a genitive person (του έμαθα) is what makes it "teach".

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