The Esperanto infinitive ends in -i: paroli “to speak,” manĝi “to eat,” esti “to be.” It names an action or state without locating it in time and without presenting it as fact, imagination, command, or wish. Dictionaries therefore list verbs in the -i form.
Form and central meaning
Replace another verb ending with -i to name the same underlying action neutrally.
| Root | Infinitive | Finite comparison |
|---|---|---|
| labor- | labori — to work | laboras — works/is working |
| vid- | vidi — to see | vidis — saw |
| ven- | veni — to come | venos — will come |
| est- | esti — to be | estu — be/should be |
Mi volas dormi.
I want to sleep.
Mi dormas.
I am sleeping.
This minimal contrast shows the difference. Dormas asserts a present situation. Dormi merely names the wanted action and depends on volas to anchor the sentence.
The infinitive has no person or number forms. Whether one person or several will perform the action, its ending remains -i.
Ŝi volas resti, sed ni volas foriri.
She wants to stay, but we want to leave.
After modal and phase verbs
Infinitives commonly follow povi “can/be able,” devi “must/have to,” and voli “want.” English uses a bare verb after “can” and “must,” but Esperanto still uses its visible infinitive ending.
Mi povas renkonti vin post la laboro.
I can meet you after work.
Ni devas sendi la formularon antaŭ vendredo.
We have to send the form before Friday.
Ĉu vi volas trinki ion? — Jes, mi volas provi tiun sukon.
Would you like something to drink? — Yes, I want to try that juice.
Verbs of beginning, continuing, and stopping also take an infinitive. The main finite verb contributes phase or attitude; the infinitive contributes the central action.
Ekpluvis, kiam ni komencis promeni.
It started raining when we began walking.
Bonvolu ĉesi frapi la tablon.
Please stop tapping the table.
Together the two verbs behave much like one complex predicate. The infinitive's valency determines its own object and complements: la formularon belongs to sendi, and la tablon belongs to frapi.
The understood subject
An infinitive cannot normally have an ordinary grammatical subject directly before it. It nevertheless has an understood semantic subject: someone performs its action. After voli, povi, and devi, that doer is normally the subject of the finite verb.
La infanoj volas ludi ekstere.
The children want to play outside.
The children both want and play. English behaves similarly here, so the pattern feels easy—until two possible people appear.
Marta promesis al Leo telefoni vespere.
Marta promised Leo that she would call in the evening.
By the normal control pattern, Marta is understood as the caller. Al Leo is the recipient of the promise, not the subject of telefoni. If Leo is meant to call, use an explicit clause: Marta petis, ke Leo telefonu vespere.
Marta petis, ke Leo telefonu vespere.
Marta asked Leo to call in the evening.
Some constructions explicitly associate another participant with the infinitive, especially perception and causation.
Mi aŭdis la najbarojn reveni malfrue.
I heard the neighbors return late.
Here la najbarojn is marked as the object of perception, while the neighbors are semantically the ones returning. This more advanced pattern is systematic, not permission to place any nominative subject before an infinitive. The subject control with infinitives page maps the alternatives.
An infinitive remains verb-like
Although an infinitive phrase can occupy positions similar to a noun phrase, the infinitive remains a verb. It can take a direct object, adverbs, and prepositional complements.
Ŝi esperas rapide trovi pli trankvilan loĝejon.
She hopes to quickly find a quieter home.
Ni planas morgaŭ veturi al la marbordo per trajno.
We plan to travel to the coast by train tomorrow.
Pli trankvilan loĝejon is the object of trovi. Morgaŭ, al la marbordo, and per trajno all modify veturi. The entire infinitive phrase then complements the finite verb.
The infinitive itself never takes accusative -n. Even when it fills a role comparable to a noun object, its form remains -i.
Mi amas kuiri por miaj amikoj.
I love cooking for my friends.
Infinitive phrases as subjects
An infinitive phrase can be the subject of a clause. When the clause describes the action, Esperanto normally uses an -e adverb after esti, because the description applies to the action rather than to a noun.
Lerni novan lingvon estas malfacile sed tre interese.
Learning a new language is difficult but very interesting.
Naĝi ĉi tie estas danĝere pro la fortaj fluoj.
Swimming here is dangerous because of the strong currents.
English uses an adjective—“difficult,” “dangerous”—but Esperanto uses malfacile, danĝere. This is a major transfer point. Compare a noun subject: La tasko estas malfacila.
Purpose with por
The established preposition por can introduce an infinitive of purpose. Normally the understood subject of the purpose action is the same as the subject of the main clause.
Mi eliris por aĉeti panon.
I went out to buy bread.
Ni malfermis la fenestron por enlasi freŝan aeron.
We opened the window to let in fresh air.
If the intended actor changes, use por ke plus a finite -u form: Mi malfermis la pordon, por ke la gastoj eniru. This makes the different subject explicit.
Mi malfermis la pordon, por ke la gastoj eniru.
I opened the door so that the guests could enter.
Other prepositions before infinitives are much more restricted. Anstataŭ and krom are established, while sen plus an infinitive is common in modern usage but was historically disputed. Detailed register and variation belong on infinitives after prepositions.
Time comes from context
An infinitive has no tense of its own. Its action may be simultaneous with, later than, or interpreted relative to the finite verb.
Hieraŭ mi volis telefoni al vi, sed mia telefono ne funkciis.
Yesterday I wanted to call you, but my phone wasn't working.
The wanting is past because of volis; the intended call is understood relative to that past situation. Esperanto does not change telefoni to a past infinitive. Participial constructions can state more precise relative time, but the simple infinitive is normally sufficient.
Common Mistakes
Removing -i after a modal verb
❌ Mi povas help vin morgaŭ.
Incorrect — Esperanto uses the full infinitive helpi after povas.
✅ Mi povas helpi vin morgaŭ.
I can help you tomorrow.
Giving the infinitive an ordinary subject
❌ Mi volas ŝi veni kun ni.
Incorrect — an infinitive cannot simply take ŝi as a grammatical subject.
✅ Mi volas, ke ŝi venu kun ni.
I want her to come with us.
Using an adjective to describe an infinitive action
❌ Veturi nokte estas danĝera.
Incorrect — the description applies to an action, so it needs -e.
✅ Veturi nokte estas danĝere.
Driving at night is dangerous.
Using -n on the infinitive
❌ Ŝi amas dancin.
Incorrect — the infinitive never takes accusative -n.
✅ Ŝi amas danci.
She loves dancing.
Translating every English “to” as part of the infinitive
❌ Mi iris al aĉeti lakton.
Incorrect — purpose is expressed with por, not directional al.
✅ Mi iris por aĉeti lakton.
I went to buy milk.
Key Takeaways
- -i names an action or state without tense, person, number, or mood.
- Infinitives commonly complement modal, phase, intention, and preference verbs.
- An infinitive has an understood doer but normally cannot take its own ordinary grammatical subject.
- It remains verb-like: it can take objects, adverbs, and complements, but never accusative -n itself.
- As a subject of esti, an infinitive action is normally described with an -e form.
Related Topics
- Esperanto Verbs: The Complete SystemA1 — See how six invariant endings express infinitive, tense, conditionality, and volition without person or number conjugation.
- Infinitives as ComplementsA1 — Build verb chains with an -i infinitive, assign its understood subject, and keep tense, negation, objects, and clause boundaries clear.
- Infinitives after Modal VerbsA1 — Combine povi, devi, and voli with a same-subject infinitive while keeping tense, mood, objects, and negation in the right layer.
- Infinitive SubjectsA1 — Use an infinitive phrase as a clause subject, describe its action with an adverb, and identify its understood actor clearly.
- Subject Control with InfinitivesA2 — Identify the understood actor of an infinitive after same-subject, influence, perception, causative, and purpose constructions.
- Infinitives after PrepositionsA2 — Choose the established preposition-plus-infinitive patterns and replace disfavored combinations with clauses, participles, or action nouns.