In a relative clause, kies links an already mentioned person or thing to something that belongs or relates to it: virino, kies filo estas kuracisto means “a woman whose son is a doctor.” It is the -es table word built on ki-, so its central meaning is “of which person or thing?” in a question and “of which person or thing” in a relative clause.
Building the link
Start with two independent statements:
Mi konas la virinon. Ŝia biciklo staras ekstere.
I know the woman. Her bicycle is outside.
The possessive ŝia in the second sentence points back to la virino. A relative clause replaces that possessive link with kies:
Mi konas la virinon, kies biciklo staras ekstere.
I know the woman whose bicycle is outside.
The antecedent is la virinon; the thing linked to her is biciklo. The relative clause is fully finite: biciklo is its subject and staras its verb. Kies does not replace that subject. It supplies the relation “the woman's bicycle.”
The same pattern works with a nonhuman antecedent. English speakers sometimes avoid “whose” for things and choose the heavy phrase “of which,” but Esperanto kies is completely natural with both people and things:
Ni luis apartamenton, kies fenestroj rigardas al la rivero.
We rented an apartment whose windows overlook the river.
La firmao, kies retejo hieraŭ paneis, jam solvis la problemon.
The company whose website failed yesterday has already solved the problem.
Kies never takes -j or -n
Like every table word ending in -es, kies is invariable. It never becomes kiesj or kiesn. Number and case belong to the following noun phrase according to that phrase's job inside the relative clause:
Jen la najbaro, kies hundo bojas ĉiun matenon.
Here is the neighbor whose dog barks every morning.
Jen la najbaro, kies hundojn mi prizorgis dum la semajnfino.
Here is the neighbor whose dogs I looked after during the weekend.
In the first sentence, hundo is singular and is the subject of bojas. In the second, hundojn is plural and is the object of prizorgis. The unchanged kies merely identifies the neighbor as the person to whom the dog or dogs belong.
This separates kies sharply from forms of kiu. Kiu itself can carry number and accusative marking because it occupies a noun-phrase role in its clause; kies is an attached possessor-like determiner:
Mi salutis la verkiston, kiun vi intervjuis.
I greeted the writer whom you interviewed.
Mi salutis la verkiston, kies romanon vi recenzis.
I greeted the writer whose novel you reviewed.
In kiun vi intervjuis, the writer is the object. In kies romanon vi recenzis, the novel is the object, and kies only connects the novel to the writer. See relative case inside the clause for the full kiu/kiun/kiuj/kiujn contrast.
More than ordinary ownership
The foundational use is ordinary possession or belonging:
Ĉu vi memoras la paron, kies pakaĵoj restis en la trajno?
Do you remember the couple whose bags were left on the train?
Mi ne aĉetos aparaton, kies baterio ne estas anstataŭigebla.
I will not buy a device whose battery cannot be replaced.
Esperanto also uses kies when an action noun contains an understood participant. That participant can be the semantic subject of the action:
La serpenton, pro kies mordo la infano enhospitaliĝis, oni poste kaptis.
The snake because of whose bite the child was hospitalized was later caught.
The snake did the biting, so la mordo de la serpento becomes kies mordo. The participant can instead be the semantic object:
La propono, kies malakcepton la komitato devas klarigi, revenos al la tagordo.
The proposal whose rejection the committee must explain will return to the agenda.
The committee rejected the proposal, so the underlying relation is la malakcepto de la propono. These constructions occur especially in (formal) and (academic) prose because action nouns package a whole event compactly. In everyday conversation, a finite paraphrase is often lighter:
La komitato devas klarigi, kial ĝi malakceptis la proponon.
The committee must explain why it rejected the proposal.
The action-noun use is not a license to replace every preposition plus kiu with kies. It is a defined extension of the same de relation.
When kies is not the right relative
Ask what preposition the complete independent clause requires. Kies corresponds to possessive de relations; it does not mean “from among whom,” “to whom,” “about whom,” or any other arbitrary prepositional relation.
For selection from a group, use el kiuj:
Venis kvin kandidatoj, el kiuj du jam laboris kun ni.
Five candidates came, two of whom had already worked with us.
The meaning is “two from among the five,” not something owned by the candidates. Likewise, keep the preposition required by the verb:
Tio estas la kolego, al kiu mi pruntedonis la aŭton.
That is the colleague to whom I lent the car.
Ni diskutis la raporton, pri kiu vi demandis hieraŭ.
We discussed the report that you asked about yesterday.
A particularly tempting error involves aparteni al “belong to.” Although English expresses possession, the Esperanto verb governs al:
La virino, al kiu apartenas tiu valizo, atendas ĉe la informejo.
The woman to whom that suitcase belongs is waiting at the information desk.
If you recast the idea with a noun, kies valizo is possible: la virino, kies valizo staras tie. The grammatical construction, not the English translation, determines the connector.
Tense, mood, and information flow
A kies clause has its own tense and mood. There is no English-style automatic backshift merely because the main verb is past:
Mi renkontis muzikiston, kies nova albumo aperos en Majo.
I met a musician whose new album will come out in May.
The meeting is past, while the release is future. A volitive verb is possible when the relative clause expresses a desired action:
Ni serĉas tradukiston, kies laboro estu kaj preciza kaj facile legebla.
We are looking for a translator whose work should be both accurate and easy to read.
Because kies points back to an antecedent, place the clause directly after the noun it describes whenever possible. A long intervening phrase can make the ownership link ambiguous. Commas commonly mark the boundary, especially when the antecedent is already identifiable, but punctuation does not create the relation; kies does.
— Ĉu vi konas tiun viron? — Jes, li estas la instruisto, kies filino ludas en nia teamo.
— Do you know that man? — Yes, he is the teacher whose daughter plays on our team.
This short exchange first identifies la instruisto, then adds a relationship that helps the listener place him. The difference between identifying and supplementary relative clauses is developed on nonrestrictive relative clauses.
Common Mistakes
Adding adjective or case endings to kies
❌ Mi renkontis la virinon, kiesa frato laboras kun vi.
Incorrect — kies is already a complete, invariable table word.
✅ Mi renkontis la virinon, kies frato laboras kun vi.
I met the woman whose brother works with you.
Marking kies instead of the possessed noun
❌ Jen la aŭtoro, kiesn librojn mi mendis.
Incorrect — the accusative belongs on librojn, not on kies.
✅ Jen la aŭtoro, kies librojn mi mendis.
Here is the author whose books I ordered.
Using kies for “some of whom”
❌ Aliĝis dek volontuloj, kies tri venis hodiaŭ.
Incorrect — this selects three from a group; it is not possession.
✅ Aliĝis dek volontuloj, el kiuj tri venis hodiaŭ.
Ten volunteers signed up, three of whom came today.
Ignoring the preposition required by the verb
❌ La kliento, kies apartenas la telefono, revenos posttagmeze.
Incorrect — aparteni requires al, and kies cannot be its subject.
✅ La kliento, al kiu apartenas la telefono, revenos posttagmeze.
The customer to whom the phone belongs will return this afternoon.
Key Takeaways
Kies introduces a relative relation of possession, belonging, or the subject/object relation contained in an action noun. It never takes -j or -n; the following noun receives whatever number and case its own role requires. Test difficult cases by rebuilding the independent Esperanto clause: use kies for the appropriate de relation, but retain al kiu, pri kiu, el kiuj, and other prepositional forms when those are what the clause actually demands.
Related Topics
- Kies: The Question/Relative Possessor CorrelativeA1 — Use invariant kies to ask or state whose something is, including possession and tightly related semantic roles.
- Relative Clauses with KiuA2 — How kiu, kiuj, kiun, and kiujn introduce finite clauses that identify or describe people and things.
- Relative Case inside the ClauseA2 — How the case and preposition of kiu are determined inside the relative clause, independently of the antecedent’s role.
- Nonrestrictive Relative ClausesC1 — Add supplementary information about an already identifiable referent while keeping relative marking, case, and punctuation clear.
- De-Phrases versus PossessivesB1 — Choose between compact possessive forms such as mia and fuller de-phrases, and avoid ambiguity about ownership, source, and authorship.
- Case and Number on CorrelativesA2 — Learn exactly which correlative families accept plural -j, object -n, or directional -n, and which remain invariant.