Greek has several words corresponding to English when, while, before, after, and until, but they do not merely name clock time. Each one tells the listener whether two events overlap, follow one another, repeat, or remain expected. The most important choice is between a fact viewed as real and an event still awaited.
The inventory at a glance
| Conjunction | Core relation | Typical verb pattern |
|---|---|---|
| όταν | when | indicative for past/general facts; bare dependent perfective is the usual one-off future pattern; θα is also possible with an explicitly future viewpoint |
| μόλις | as soon as | indicative for facts; dependent perfective for an awaited event |
| ενώ | while; whereas | indicative |
| καθώς | as, while | indicative |
| πριν (να) | before | dependent form, with optional να |
| αφού | after, once | indicative for facts; dependent perfective for a future endpoint |
| μέχρι/ώσπου να | until an expected endpoint | να + dependent form |
| κάθε φορά που | every time | usually indicative |
These are all standard neutral Greek. Ώσπου can sound slightly more narrative than everyday μέχρι να, but it is neither archaic nor confined to literature.
όταν: past facts, habits, and future events
With a past event or a general habit, όταν introduces something treated as a fact, so the verb is indicative.
Όταν ήμουν παιδί, περνούσα κάθε καλοκαίρι στο χωριό.
ótan ímun pedhí, pernúsa káthe kalokéri sto chorió
When I was a child, I spent every summer in the village.
Όταν βρέχει, παίρνω το λεωφορείο.
ótan vréchi, pérno to leoforío
When it rains, I take the bus.
For a single future completion, Greek very commonly puts the perfective dependent form directly after όταν, without να. This is the neutral learner default; the main clause normally carries θα.
Όταν τελειώσω τη δουλειά, θα σου τηλεφωνήσω.
ótan telióso ti dhuliá, tha su tilefoníso
When I finish work, I'll call you.
Τελειώσω is not a present indicative: it is the perfective non-past form also found after να. Here όταν itself licenses it. This is why English when I will finish and Greek do not line up word for word.
That default does not make όταν + θα ungrammatical. Greek can retain θα when the temporal situation is explicitly viewed as future—especially for an ongoing or repeated future period, or for future-in-the-past—and θα can also occur with a one-off future event. Compare this explicitly future setting:
Όταν θα μένουμε στην Αθήνα, θα βλέπουμε πιο συχνά τους φίλους μας.
ótan tha ménume stin Athína, tha vlépume pio sichná tus fílus mas
When we're living in Athens, we'll see our friends more often. (explicit future period)
For a simple future endpoint, όταν τελειώσω remains the concise, very common choice. The sound rule is therefore “do not insert θα mechanically,” not “όταν θα never exists.”
μόλις and αφού: one event before another
Μόλις means “as soon as” and makes the interval between events minimal. Like όταν, it uses an indicative for a fact and a dependent perfective form for an awaited future event.
Μόλις φτάσεις, στείλε μου μήνυμα.
mólis ftásis, stíle mu mínima
As soon as you arrive, send me a message.
Αφού presents its event as earlier than the main event: “after,” “once,” or “after having.” A completed past fact takes the indicative.
Αφού έφαγαν, βγήκαν για μια βόλτα.
afú éfaghan, vyíkan ya mia vólta
After they ate, they went out for a walk.
With a future endpoint, αφού commonly takes the perfective dependent form directly, again without να.
Αφού τελειώσεις, κλείσε τον υπολογιστή.
afú teliósis, klíse ton ipoloyistí
After you finish, shut down the computer.
Αφού can also mean “since/given that” when the relation is logical rather than temporal. Context distinguishes “after you know it” from “since you know it”; that overlap is real and must be learned from the whole sentence.
ενώ and καθώς: events unfolding together
Ενώ commonly marks simultaneity: one event is in progress while another occurs. It can also oppose two facts, corresponding to English whereas.
Ενώ μαγείρευα, ο Πέτρος έστρωνε το τραπέζι.
enó mayíreva, o Pétros éstrone to trapézi
While I was cooking, Petros was setting the table.
Ενώ η Μαρία θέλει να φύγει, ο Νίκος προτιμά να μείνει.
enó i María théli na fíyi, o Níkos protimá na míni
Whereas Maria wants to leave, Nikos prefers to stay.
Καθώς also means “as/while” when two developments unfold together. It is common in narration and careful speech, and it can additionally mean “since/because”; again, the surrounding logic resolves the reading.
Καθώς περπατούσαμε, άρχισε να χιονίζει.
kathós perpatúsame, árchise na chionízi
As we were walking, it began to snow.
πριν, μέχρι να, and ώσπου να
Before a verb, πριν takes the dependent form; να is optional. Both πριν φύγεις and πριν να φύγεις are standard. Before a noun or time expression, use πριν από instead.
Πριν φύγεις, κλείσε όλα τα παράθυρα.
prin fíyis, klíse óla ta paráthira
Before you leave, close all the windows.
An expected endpoint uses μέχρι να or ώσπου να. The activity continues up to an event that has not yet been realized from the relevant viewpoint.
Θα περιμένω μέχρι να γυρίσεις.
tha periméno méchri na yirísis
I'll wait until you come back.
For a realized past boundary, ώσπου can instead take an indicative.
Δούλευαν ώσπου νύχτωσε.
dhúlevan óspu níchtose
They worked until night fell.
The fuller system of clause placement, commas, and multi-event timelines belongs to temporal clauses.
Repeated occasions
Κάθε φορά που means “every time.” The event is presented as a recurring fact, so an indicative is normal.
Κάθε φορά που βγαίνει έξω, παίρνει τα κλειδιά του.
káthe forá pu vyéni ékso, pérni ta klidhiá tu
Every time he goes out, he takes his keys.
English often uses one flexible when for all these relations. Greek makes you choose whether the meaning is “whenever,” “as soon as,” “while,” “before,” or “until”—but that choice also makes the event structure much clearer.
Common Mistakes
1. Adding να after ενώ. Ενώ introduces a factual simultaneous or contrasting clause, not a να-clause.
❌ Ενώ να μαγείρευα, χτύπησε το τηλέφωνο.
Incorrect—ενώ takes the indicative here.
✅ Ενώ μαγείρευα, χτύπησε το τηλέφωνο.
enó mayíreva, chtípise to tiléfono
While I was cooking, the phone rang.
2. Using πριν από directly before a verb. Από belongs before a noun or time expression.
❌ Πριν από φύγεις, σβήσε το φως.
Incorrect—before a verb use πριν or πριν να, without από.
✅ Πριν φύγεις, σβήσε το φως.
prin fíyis, zvíse to fos
Before you leave, turn off the light.
3. Using αφού directly before a noun. Αφού introduces a clause; English “after + noun” normally corresponds to μετά + noun.
❌ Αφού την ταινία, φύγαμε.
Incorrect—αφού must introduce a clause; before a noun use μετά.
✅ Μετά την ταινία, φύγαμε.
metá tin tenía, fíghame
After the film, we left.
Key Takeaways
- Όταν + indicative presents past or recurring facts; a single future endpoint commonly uses όταν + perfective dependent form. Όταν + θα is also grammatical when an explicitly future viewpoint is relevant.
- Μόλις minimizes the interval; αφού marks an earlier event. Both commonly use a dependent perfective form for an awaited future endpoint.
- Ενώ/καθώς express simultaneity; ενώ also means “whereas.”
- Πριν (να) has optional να, while an expected endpoint takes μέχρι/ώσπου να.
- Κάθε φορά που marks repeated occasions.
Related Topics
- Temporal ClausesA2 — Arrange Greek time clauses before, inside, or after the main clause to build clear sequences of earlier, simultaneous, and later events.
- να After πριν, μέχρι, χωρίς, αντίB2 — A family of subordinators — πριν (before), μέχρι / ώσπου (until), χωρίς (without), αντί (instead of), εκτός από (except) — that switch to a full να-clause the moment a verb follows, turning what English does with 'before doing / without doing' into a conjugated Greek clause.
- Subordinating Conjunctions OverviewA2 — Navigate Greek dependent clauses by function: complements, time, cause, purpose, result, concession, and condition, with the mood and aspect patterns each linker interacts with.