Adjectives such as preta, kapabla, libera, ema, and volonta can be followed by an infinitive in -i: Mi estas preta foriri “I am ready to leave.” The adjective describes a person or thing; that same referent is normally understood as the performer of the infinitive action.
A different pattern evaluates the action itself: Estas facile erari “It is easy to make a mistake.” Here Esperanto uses the E-word facile, because the infinitive is verb-like. English uses an adjective after it is, so this A/E distinction is a major transfer point.
The described referent controls the action
In Ana estas preta komenci, preta describes Ana and Ana is the understood subject of komenci. The infinitive never marks person or number; the adjective shows agreement with the described referent.
Mi estas preta komenci la kunvenon.
I am ready to begin the meeting.
La teknikistoj estas pretaj instali la novan programon.
The technicians are ready to install the new software.
Plural teknikistoj requires pretaj. The infinitive instali remains unchanged.
Ĉu vi estas kapabla ripari ĉi tiun aparaton?
Are you capable of repairing this device?
The implied subject of ripari is vi, the same person described by kapabla. A bare infinitive directly after the adjective is established and natural Esperanto.
Attributive adjectives with infinitives
The adjective-plus-infinitive unit can describe a noun inside a larger phrase. The adjective agrees with that noun; the infinitive does not.
Ni bezonas kunlaborantojn kapablajn labori sendepende.
We need collaborators capable of working independently.
Kapabla-j-n agrees with object kunlaborant-o-j-n. The people, not the speaker, are understood to perform labori.
La kompanio serĉas teknikiston pretan vojaĝi ofte.
The company is looking for a technician ready to travel frequently.
Postposition keeps the adjective close to its infinitive. A long preposed string such as pretan ofte vojaĝi teknikiston is difficult to parse; use the postposed unit or a relative clause.
La kompanio serĉas teknikiston, kiu pretas vojaĝi ofte.
The company is looking for a technician who is ready to travel frequently.
The relative clause is especially useful when the controller might otherwise be unclear.
Bare infinitive or por + infinitive
With adjectives of readiness and ability, both a bare infinitive and por + infinitive are attested when the infinitive names an intended action: preta foriri / preta por foriri, kapabla instrui / kapabla por instrui. The bare infinitive is compact and directly linked to the adjective; por can emphasize suitability or preparation for the action.
La salono estas preta por akcepti la gastojn.
The hall is ready to receive the guests.
Here the hall cannot act intentionally, but its state makes receiving guests possible. Por makes the purpose reading transparent.
Mi jam estas preta respondi viajn demandojn.
I am now ready to answer your questions.
Here the human controller and intended action are obvious, so the bare infinitive is direct. This is accepted variation, not a difference between correct and incorrect Esperanto. For learners, use the bare infinitive after a personal adjective when the controller is clear, and por when purpose or suitability needs emphasis.
When the action itself is easy, important, or pleasant
If the infinitive is the subject-like action being evaluated, use an E-word: facile, malfacile, grave, necese, agrable, danĝere. There is no noun for an A-word to agree with.
Estas facile forgesi pasvorton, kiun oni malofte uzas.
It is easy to forget a password that one rarely uses.
Estas grave konservi kopion de la dokumento.
It is important to keep a copy of the document.
Resti sola sur la monto nokte estas danĝere.
Staying alone on the mountain at night is dangerous.
The foundational principle is regular: A-words describe noun-like referents, while E-words describe actions and clauses. Compare this minimal pair:
For the broader syntax of an infinitive functioning as the action under discussion, see Infinitive Subjects.
La ekzameno estas facila, sed estas facile mislegi unu el la demandoj.
The exam is easy, but it is easy to misread one of the questions.
Facila agrees with noun ekzameno. Facile evaluates mislegi.
English dummy it has no Esperanto counterpart here. Do not insert ĝi in Ĝi estas facile... unless ĝi refers to an actual previously mentioned thing.
Easy to read: two clear rewrites
English often makes an object the subject of an easy to... construction: “This book is easy to read.” Esperanto has two especially clear strategies:
Estas facile legi ĉi tiun libron.
It is easy to read this book.
Ĉi tiu libro estas facile legebla.
This book is easily readable.
The first evaluates the action and keeps libron as the object of legi. The second uses -ebl- to form legebla, “able to be read,” modified by E-word facile. Avoid mechanically producing ĉi tiu libro estas facila legi, whose controller and relation are unclear.
The same contrast works negatively:
La instrukcioj ne estas facile kompreneblaj sen ekzemplo.
The instructions are not easy to understand without an example.
Plural instrukcioj requires kompreneblaj. Facile modifies that adjective and remains invariant.
Scope and omitted nouns
An infinitive attaches to the adjective immediately opening that semantic slot. In volontuloj pretaj kaj kapablaj helpi, ordinary interpretation can let helpi relate to both adjectives. If only one relation is intended, repeat or restructure.
Ni bezonas homojn pretajn ekiri tuj kaj kapablajn labori nokte.
We need people ready to leave immediately and capable of working at night.
Agreement marks both adjectives as descriptions of homojn; separate infinitives make their scope explicit.
An adjective may remain after an omitted noun when context supplies it: la pretaj foriri “those ready to leave.” It keeps the A-ending and plural agreement; it does not become an O-word.
— Kiuj povas ekiri nun? — La pretaj foriri povas veni kun mi.
— Who can leave now? — Those ready to leave can come with me.
Common Mistakes
1. Using an adjective to evaluate an infinitive
❌ Estas grava respondi hodiaŭ.
Incorrect: the infinitive action requires the E-word grave.
✅ Estas grave respondi hodiaŭ.
It is important to answer today.
2. Making the infinitive agree
❌ Ili estas pretaj foriraj.
Incorrect: an infinitive always keeps its -i ending.
✅ Ili estas pretaj foriri.
They are ready to leave.
3. Leaving an attributive adjective uninflected
❌ Ni dungis homojn kapabla solvi la problemon.
Incorrect: kapabla describes a plural direct object.
✅ Ni dungis homojn kapablajn solvi la problemon.
We hired people capable of solving the problem.
4. Copying the English easy-to construction
❌ Ĉi tiu instrukcio estas facile kompreni.
Incorrect: an E-word plus a bare infinitive cannot make instrukcio the described readable thing.
✅ Ĉi tiu instrukcio estas facile komprenebla.
This instruction is easy to understand.
5. Assigning the action to the wrong controller
❌ La direktoro parolis kun la teknikistoj preta helpi.
Unclear and mismatched: preta does not visibly attach to the plural technicians who are meant to help.
✅ La direktoro parolis kun la teknikistoj, kiuj estis pretaj helpi.
The director spoke with the technicians, who were ready to help.
Key Takeaways
After preta, kapabla, and similar adjectives, the described referent normally performs the following infinitive. The adjective agrees; the infinitive never does. Bare infinitives and por + infinitive are both established in suitable contexts. When the action itself is easy, important, or dangerous, use an E-word: Estas facile fari, not estas facila fari.
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Start learning Esperanto →Related Topics
- Adjective ComplementsA2 — How Esperanto adjectives complete their meaning with prepositional phrases and clauses while preserving agreement and clear attachment.
- Adjectives after EstiB2 — How predicative adjectives after esti describe the subject, agree in number, and remain outside the accusative.
- The Infinitive in -IA1 — Use the invariant -i form to name an action or state without asserting tense, person, or mood.
- 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.
- -ebl-: Passive PossibilityB1 — Use -ebl- to describe something as capable of undergoing the action of a transitive base verb.