A relative clause is not simply a clause beginning with που or ο οποίος. It is a clause anchored to a head noun, and its position, punctuation, and internal agreement tell the reader how that noun should be understood. The relativizers themselves are covered on relative που, ο οποίος, and resumptive pronouns. Here the focus is the architecture of the whole sentence.
A relative clause follows its head
The neutral pattern is head noun phrase + relative clause. Keeping them adjacent lets the reader identify the attachment before processing the rest of the sentence.
Η γειτόνισσα που μας πότισε τα φυτά άφησε τα κλειδιά στη θυρίδα.
i yitónisa pu mas pótise ta fitá áfise ta klidhiá sti thirídha
The neighbour who watered our plants left the keys in the letter box.
Βρήκα το αρχείο που ζητούσες στον παλιό υπολογιστή.
vríka to archío pu zitúses ston palió ipoloyistí
I found the file you wanted on the old computer.
That order is more than style. If another plausible noun intervenes, attachment can become unclear:
Μίλησα με τη γραμματέα του διευθυντή που επέστρεψε χθες.
mílisa me ti ghramatéa tu dhiefthindí pu epéstrepse chthes
I spoke with the manager's secretary who returned yesterday. (ambiguous: the secretary or the manager?)
A declined relative can resolve the ambiguity because its gender points to one noun:
Μίλησα με τη γραμματέα του διευθυντή, η οποία επέστρεψε χθες.
mílisa me ti ghramatéa tu dhiefthindí, i opía epéstrepse chthes
I spoke with the manager's secretary, who returned yesterday. (formal; η οποία points to the secretary)
In (informal) speech, a heavy που-clause may be postponed after other material. This is grammatical, but it increases processing load:
Γνώρισα έναν άνθρωπο χθες που είχε ζήσει τριάντα χρόνια στην Αφρική.
ghnórisa énan ánthropo chthes pu íche zísi triánda chrónia stin Afrikí
I met a man yesterday who had lived in Africa for thirty years. (informal; postponed relative)
Careful speech and writing normally restore adjacency: Χθες γνώρισα έναν άνθρωπο που είχε ζήσει… There is no mechanical word limit on separation; the real constraint is recoverability. The farther the clause travels, the more likely another noun or time expression will compete as its head.
Restrictive versus non-restrictive: commas change the claim
A restrictive relative selects a subset. A non-restrictive relative adds information about a referent already identified. Greek can use που for both; the commas and spoken pauses carry the distinction.
Οι υπάλληλοι που τελείωσαν τη βάρδια έφυγαν.
i ipálili pu telíosan ti várdhia éfighan
The employees who finished their shift left. (only that subset)
Οι υπάλληλοι, που τελείωσαν τη βάρδια, έφυγαν.
i ipálili, pu telíosan ti várdhia, éfighan
The employees, who had finished their shift, left. (all the employees; the clause adds background)
The first clause is essential for identifying which employees left. The second assumes the employees are already identified and states their completed shift as an additional fact. This is a meaning difference, not ornamental punctuation.
With ο οποίος, non-restrictive relatives are especially common in formal and journalistic prose (formal), but they are not obligatory there. Που inside commas remains grammatical and natural.
Agreement comes from the clause-internal subject
The verb inside the relative clause agrees with its own subject. If the head noun is the missing subject, the verb agrees with the head. If the head is an object, the verb agrees with whatever subject appears inside the relative clause.
Οι φοιτητές που παρουσίασαν την εργασία απάντησαν σε όλες τις ερωτήσεις.
i fitités pu parusíasan tin erghasía apándisan se óles tis erotísis
The students who presented the project answered every question.
Οι φοιτητές που κάλεσε η καθηγήτρια περίμεναν έξω.
i fitités pu kálese i kathiyítria perímenan ékso
The students whom the lecturer called waited outside.
In the first sentence, οι φοιτητές is the subject of παρουσίασαν, hence plural. In the second, it is the object of κάλεσε; the singular subject is η καθηγήτρια, so κάλεσε remains singular. English word order helps less here because its relative marker often hides the grammatical role.
Person agreement also survives across the boundary:
Εσείς που γνωρίζετε τη διαδικασία μπορείτε να βοηθήσετε τους καινούριους.
esís pu ghnorízete ti dhiadhikasía boríte na voithísete tus kenúrius
Those of you who know the procedure can help the newcomers.
The antecedent εσείς requires second-person plural γνωρίζετε, not a default third person.
Case marking stays inside the relative clause
Everyday που carries no case. For roles such as recipient or prepositional object, Greek marks the relation inside the clause; formal ο οποίος can carry it itself.
Ο πελάτης που του στείλαμε τα έγγραφα ζήτησε διευκρινίσεις.
o pelátis pu tu stílame ta éngrafa zítise dhiefkrinísis
The client we sent the documents to asked for clarification.
Ο πελάτης στον οποίο στείλαμε τα έγγραφα ζήτησε διευκρινίσεις.
o pelátis ston opío stílame ta éngrafa zítise dhiefkrinísis
The client to whom we sent the documents asked for clarification. (formal)
These two sentences differ in register, not truth. The choice belongs to που versus ο οποίος; syntactically, both ensure that the recipient role is expressed exactly once.
Relative clauses can be nested
One relative clause may contain a noun that heads another relative. Parse each head + clause pair locally.
Το άρθρο που έγραψε ο δημοσιογράφος που γνώρισες κέρδισε βραβείο.
to árthro pu éghrapse o dhimosioghráfos pu ghnórises kérdhise vravío
The article written by the journalist you met won an award.
The outer clause που έγραψε… modifies το άρθρο. Inside it, που γνώρισες modifies ο δημοσιογράφος. Because the second relative sits immediately after ο δημοσιογράφος, its attachment is clear.
Longer chains are grammatical but hard to follow. In edited prose, split the sentence or alternate που and ο οποίος where the heavier form genuinely clarifies an antecedent.
Common Mistakes
1. Leaving a relative verb in the third person after a second-person head.
❌ Εσείς που γνωρίζει τη διαδικασία μπορείτε να βοηθήσετε.
Incorrect—the head is second-person plural εσείς, so the relative verb must be γνωρίζετε.
✅ Εσείς που γνωρίζετε τη διαδικασία μπορείτε να βοηθήσετε.
esís pu ghnorízete ti dhiadhikasía boríte na voithísete
Those of you who know the procedure can help.
2. Letting two nested clauses share one relative marker. Each head + clause relation needs its own marker: the first που below links the book to εξέδωσε, and the second links the press to γνωρίζεις.
✅ Το βιβλίο που εξέδωσε ο οίκος που γνωρίζεις έγινε επιτυχία.
to vivlío pu eksédhose o íkos pu ghnorízis éyine epitichía
The book published by the press you know became a success.
3. Putting a preposition directly before invariable που.
❌ Ο άνθρωπος στον που μίλησα εργάζεται στον δήμο.
Incorrect—a preposition cannot govern που; use στον οποίο or put the role inside a που-clause.
✅ Ο άνθρωπος στον οποίο μίλησα εργάζεται στον δήμο.
o ánthropos ston opío mílisa ergházete ston dhímo
The man I spoke to works for the municipality. (formal)
Key Takeaways
- Keep the relative clause beside its head; postponement is possible (informal) but must not create attachment ambiguity.
- In standard writing, no commas signal a restrictive reading; paired commas signal a non-restrictive reading and change the claim.
- The relative verb agrees with its own subject, not automatically with the head noun.
- Nested relatives are parsed as local head-and-clause pairs; long chains should be reorganized for clarity.
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- The Relative πουA2 — One tiny word covers English who, whom, which and that, and it never changes shape: που is invariable for gender, number and case, so ο άντρας που ήρθε, η γυναίκα που ήρθε and τα παιδιά που ήρθαν all use the same form. Covers why που can never be dropped the way English drops 'that', the non-noun antecedents (τη μέρα που, τώρα που, εκεί που), restrictive against non-restrictive, and the person agreement in Εσύ που ξέρεις.
- The Relative ο οποίοςB2 — The declinable relative of written Greek: ο οποίος / η οποία / το οποίο takes its gender and number from the antecedent and its case from its own job inside the clause, so η εταιρεία της οποίας ο διευθυντής παραιτήθηκε is 'the company whose director resigned'. Full paradigm, the obligatory article, the genitive that translates English 'whose', and where the form actually lives — journalism, academic prose, law and official documents.
- Resumptive Pronouns in που-ClausesC1 — Because που carries no case, a clitic inside the clause has to carry it instead: ο άνθρωπος που του μίλησα, η γυναίκα που της έδωσα το δώρο, ο συγγραφέας που διάβασα το βιβλίο του. The rule role by role — required for the genitive (indirect object and possessor) and for prepositional objects, absent for the subject and for a restrictive direct object, absent again for place and time — plus why this is not clitic doubling and where the clitic stands.
- που vs ο οποίοςB2 — Both are correct Greek and the axis between them is register plus explicitness, not right and wrong: που is light, invariable and covers nine sentences out of ten; ο οποίος marks gender, number and case, which buys you clarity in writing and costs you naturalness in speech. A context-by-context table, the two places where the choice disappears, how ο οποίος fixes an ambiguous attachment, and why piling on ο οποίος in conversation backfires.