Esperanto usually expresses “each other” or “one another” with unu ... (la) alia. The expression represents a compressed reciprocal scene: one member acts toward another, and the relationship holds across the group. The grammatical role of alia determines whether it takes accusative -n or a preposition.
The core reciprocal pattern
In Ili amas unu la alian, imagine the expanded meaning “one loves the other; each loves each other member.” Unu represents the acting side of the reciprocal relation, while la alian represents the affected side.
La du fratinoj tre amas unu la alian.
The two sisters love each other very much.
Ni helpis unu la alian dum la translokiĝo.
We helped each other during the move.
Ĉu vi ankoraŭ vidas unu la alian ofte?
Do you still see each other often?
Because ami, helpi, and vidi take direct objects, alia appears as alian. The fixed-looking English phrase “each other” hides this syntax; Esperanto displays the role with its normal case system.
The article is often present—unu la alian—but unu alian is also accepted in the reciprocal construction. The version with la is a reliable neutral default and makes the paired relationship especially clear.
Choose the preposition required by the relationship
When the second participant is not a direct object, put the appropriate preposition before (la) alia. With non-directional relations such as al, kun, pri, and de below, do not add accusative -n merely because English treats “each other” as an object. Spatial prepositions can still take directional -n by the ordinary rule: La katoj saltis unu sur la alian “The cats jumped onto each other.”
| Relationship | Reciprocal form | Underlying idea |
|---|---|---|
| recipient/direction | unu al la alia | one gives or speaks to another |
| companionship | unu kun la alia | one is or acts with another |
| topic | unu pri la alia | one speaks or thinks about another |
| source/possession | unu de la alia | one receives or differs from another |
La amikoj sendas voĉmesaĝojn unu al la alia ĉiutage.
The friends send voice messages to each other every day.
Post la disputo ili ne volis paroli unu kun la alia.
After the argument they did not want to speak with each other.
La kolegoj sciis surprize malmulte unu pri la alia.
The colleagues knew surprisingly little about each other.
La du versioj multe diferencas unu de la alia.
The two versions differ greatly from each other.
The preposition belongs to the second, non-subject role in the compressed relationship. Unu normally remains unmarked because it represents the subject of the imagined small clause.
Reflexive versus reciprocal meaning
Reflexive sin normally sends an action back to the same subject participant; unu la alian distributes it between distinct members. Compare:
La infanoj lavis sin antaŭ la vespermanĝo.
The children washed themselves before dinner.
La infanoj lavis unu la alian post la kota ludo.
The children washed each other after the muddy game.
The first allows each child to wash their own body. The second says that child A washed child B and reciprocal washing occurred. English “themselves” and “each other” preserve a similar contrast, but Esperanto bare sin can occasionally acquire a reciprocal interpretation when context makes it unmistakable.
To state reciprocity with sin explicitly, add reciproke:
La kandidatoj publike kritikis sin reciproke.
The candidates publicly criticized each other.
This is equivalent in core meaning to La kandidatoj kritikis unu la alian. Bare sin would risk the reading that each candidate criticized themself. For learners and careful prose, unu la alian or sin reciproke is the better signal.
Do not combine the two full markers: Ili amas sin unu la alian redundantly and incorrectly mixes constructions. Choose one.
First, second, and third person
The reciprocal phrase is independent of grammatical person. It works with ni, vi, ili, nouns, and even coordinated singular subjects.
Ni konas unu la alian de pli ol dudek jaroj.
We have known each other for more than twenty years.
Vi du devas aŭskulti unu la alian.
You two must listen to each other.
Marta kaj Leono ridetis unu al la alia trans la tablo.
Marta and Leon smiled at each other across the table.
The forms do not agree with ni, vi, or ili. Their apparent singular is part of the distributive logic: take one member in relation to another member.
— Ĉu vi kaj Sam ankoraŭ skribas unu al la alia? — Jes, preskaŭ ĉiusemajne.
— Do you and Sam still write to each other? — Yes, almost every week.
Singular and plural variants
The ordinary reciprocal uses singular unu and alia even for a large group. Plural unuj ... la aliaj is possible when the intended contrast is between subgroups rather than individual pairings.
Dum la paŭzo, unuj studentoj diskutis kun la aliaj.
During the break, some students discussed with the others.
That sentence divides the students into plural sets. It is not simply a more agreeing version of unu kun la alia. Use the singular reciprocal for the general “each other” meaning.
The base form unu never takes accusative -n. Unun is nonstandard even when a learner imagines the first element as an object. The rare plural pronominal form unujn can take -n, but it serves special subgroup structures, not the ordinary reciprocal.
Other reciprocal resources
Esperanto also uses inter si/inter ni/inter vi and verbs with inter-. These can be more compact:
La teamanoj dividis la taskojn inter si.
The team members divided the tasks among themselves.
Ni interparolis ĝis malfrua nokto.
We talked with each other until late at night.
Inter si is partly conventional and does not always follow every ordinary local-antecedent restriction on si. Interparoli lexicalizes mutual conversation. These are accepted alternatives, not word-for-word transformations suitable for every verb.
For a neutral expression that works productively with almost any relation, unu ... la alia remains the clearest choice.
Norm, variation, and style
The reciprocal construction is established in foundational and classical usage. Variation between unu la alian and unu alian is accepted. Modern speakers also alternate it with reciproke, inter si, and conventional inter- verbs.
In (formal) prose, choose the construction that makes participant roles explicit. A sentence such as La landoj akuzis sin can be reflexive or reciprocal in principle; La landoj akuzis unu la alian unambiguously states mutual accusation.
See The Reflexive Pronoun Si for the local reflexive system that this reciprocal construction contrasts with.
Common Mistakes
Omitting object -n
❌ La najbaroj salutas unu la alia ĉiumatene.
Incorrect — the other participant is the direct object of salutas.
✅ La najbaroj salutas unu la alian ĉiumatene.
The neighbors greet each other every morning.
Adding -n after al
❌ Ili donis donacojn unu al la alian.
Incorrect — al already marks the recipient role.
✅ Ili donis donacojn unu al la alia.
They gave gifts to each other.
Creating the forbidden form unun
❌ La du proponoj ekskludas unun la alian.
Incorrect — unu never takes accusative -n.
✅ La du proponoj ekskludas unu la alian.
The two proposals exclude each other.
Combining reciprocal constructions
❌ La partneroj respektas sin unu la alian.
Incorrect — sin and unu la alian duplicate incompatible structures.
✅ La partneroj respektas unu la alian.
The partners respect each other.
Key Takeaways
- Unu ... (la) alia expresses reciprocal action between members of a group.
- Put accusative -n on alia for a direct object; otherwise use the relation’s preposition.
- Unu normally represents the subject side and never becomes unun.
- Sin is basically reflexive; use sin reciproke or unu la alian to make reciprocity explicit.
- Singular forms are the neutral reciprocal; plural forms highlight subgroups.
Related Topics
- The Reflexive Pronoun SiA1 — Use si and sin when a third-person subject refers back to itself, and distinguish reflexive reference from ordinary third-person pronouns.
- Clause Boundaries for SiA1 — Track si and sia within finite clauses so that reflexive reference stays with the correct local subject.
- Direct ObjectsA1 — Learn which Esperanto verb complements are direct objects, how -n marks them, and how object marking remains stable when word order changes.
- Pronouns after PrepositionsB2 — Use basic, reflexive, and directional pronoun forms accurately after Esperanto prepositions.
- Coordination of PhrasesC1 — Coordinate parallel subjects, objects, complements, and modifiers while preserving case, scope, and clear constituent boundaries.