Lasi is the regular transitive verb for two closely related ideas: leaving an object in a place or state, and allowing an object to perform an action. In those core uses, the subject refrains from taking, changing, or obstructing something. A resultative extension can instead foreground the state or trace that remains after an event. This logic distinguishes lasi iun fari “let someone do” from active causation with igi iun fari “make someone do.”
Complete regular paradigm
| Form | Function | Typical translation |
|---|---|---|
| lasi | infinitive | to leave, to let |
| lasas | present indicative | leave(s), let(s) |
| lasis | past indicative | left, let |
| lasos | future indicative | will leave, will let |
| lasus | conditional | would leave, would let |
| lasu | volitive | leave!, let! |
There is no stem change and no person agreement: mi lasas, ŝi lasas, ili lasas. The endings contribute tense or mood exactly as they do with other regular verbs.
Mi lasos la rezervan ŝlosilon ĉe la najbaroj.
I'll leave the spare key with the neighbors.
Ĉu vi lasus vian biciklon ekstere dum la tuta nokto?
Would you leave your bicycle outside all night?
Lasu la pakaĵon ĉe la akceptejo, se mi ne estas en la oficejo.
Leave the package at reception if I'm not in the office.
Leaving something in a place
Lasi normally has an object: the person or thing that is not taken along. A location phrase describes where that object remains.
Ŝi lasis sian telefonon sur la kuireja tablo.
She left her phone on the kitchen table.
Ne lasu manĝaĵon en la aŭto dum varma tago.
Don't leave food in the car on a hot day.
The local complements here are static: sur la tablo, en la aŭto. They describe the place in which the object remains, not a path into that place. This contrasts with meti la telefonon sur la tablon, which explicitly causes movement to an endpoint.
English “leave” also means depart. Esperanto normally uses intransitive foriri when no abandoned object is named:
Mi devas foriri nun, sed mi lasos mesaĝon por vi ĉe la akceptejo.
I have to leave now, but I'll leave a message for you at reception.
Mi lasas nun is incomplete for “I'm leaving now,” because lasi invites the question “What are you leaving?” Use foriri for the departing person, forlasi lokon when a place is treated as an object that one leaves or abandons.
Leaving an object in a state
An object can be followed by a predicative adjective or participle naming the state that continues. The object has accusative -n; the predicative description agrees in number but does not take -n.
Bonvolu lasi la fenestron malfermita dum la farbo sekiĝas.
Please leave the window open while the paint dries.
La novaĵoj lasis ĉiujn silentaj dum kelkaj minutoj.
The news left everyone silent for several minutes.
In the second example, the news causes a new state; lasi profiles the silence that remains as the event's result. This result-state pattern does not turn lasi iun fari into an active causative: with an infinitive, lasi still normally means allowing or not preventing the action.
In lasi la fenestron malfermita, la fenestron is the object and malfermita describes its continuing state. La malfermitan fenestron would instead be one noun phrase meaning “the open window.” With a plural object, use lasi la pordojn malfermitaj, still without accusative on the predicative.
State can also be expressed by a prepositional phrase:
Lasu min en paco ĝis mi finos ĉi tiun kalkulon.
Leave me in peace until I finish this calculation.
Other frequent combinations include lasi ion netuŝita “leave something untouched,” lasi demandon nerespondita “leave a question unanswered,” and lasi impreson/spuron “leave an impression/trace.”
Allowing someone to act: lasi iun fari
With an infinitive, lasi normally means permit or refrain from preventing an action. The object of lasi is the understood performer of the infinitive.
La instruisto lasis la studentojn fini la diskuton antaŭ la paŭzo.
The teacher let the students finish the discussion before the break.
Lasu min klarigi, kio okazis, antaŭ ol vi decidos.
Let me explain what happened before you decide.
Min is grammatically the object of lasu and semantically the subject of klarigi. Since infinitives have no personal endings, the object supplies their performer.
When the infinitive is itself transitive, keep each object near its own verb to avoid ambiguity:
La gepatroj lasis la infanojn spekti la filmon ĝis la fino.
The parents let the children watch the film to the end.
La infanojn belongs to lasis and performs the watching; la filmon belongs to spekti and is watched. This structure is explained more broadly under Objects after Infinitives.
The performer can sometimes be omitted when context supplies it, but this creates possible ambiguity, especially with a transitive infinitive. Clear modern prose normally states the performer when readers could misunderstand who does what.
Attested usage also sometimes places the performer after the infinitive, as in the traditional pattern lasi fali la manojn. That order is accepted when roles are obvious and appears especially in (literary) texts and set expressions, but it can become genuinely ambiguous with two transitive verbs. The practical recommendation is lasi + performer + infinitive + infinitive's object: lasi la infanojn spekti la filmon.
— Ĉu mi povas malfermi la fenestron? — Jes, sed ne lasu la katon eliri.
— May I open the window? — Yes, but don't let the cat get out.
The negative scopes over permission or prevention: ne lasu la katon eliri means prevent the cat from leaving, literally “do not allow it to leave.”
Lasi versus igi
The two verbs can share the surface frame verb + object + infinitive, but they encode opposite kinds of involvement.
| Pattern | Subject's role | Meaning |
|---|---|---|
| lasi iun fari | permits or does not prevent | let someone do |
| igi iun fari | actively causes or compels | make someone do |
La direktoro lasis nin labori hejme, sed la paneo igis nin ĉesigi la laboron.
The director let us work from home, but the outage made us stop working.
PMEG notes historical examples in which lasi + infinitive was used under national-language influence for active commissioning. The modern pedagogical recommendation is clear: reserve lasi for permission or non-prevention and use igi, -igi, or -igi's compact derivative when active causation is meant.
Mi farigis novan ŝlosilon post kiam mi perdis la originalon.
I had a new key made after I lost the original.
English “have something done” is active commissioning, so farigi, not lasi fari, is the reliable modern choice.
“Let's” is normally ni + -u
English let's is historically an imperative involving “let,” but ordinary Esperanto proposals use the volitive verb with ni.
Ni iru hejmen antaŭ ol komenciĝos la pluvego.
Let's go home before the downpour starts.
Lasu nin iri is grammatical when it literally means “allow us to go,” perhaps addressed to someone blocking departure. It is not the neutral translation of every English “let's.”
Participles and productive derivatives
| Time relation | Active | Passive |
|---|---|---|
| ongoing | lasanta — leaving/letting | lasata — being left/allowed |
| earlier/completed | lasinta — having left/let | lasita — left |
| later/intended | lasonta — about to leave/let | lasota — to be left |
La lasita pakaĵo blokis la elirejon, do sekurecgardisto formovis ĝin.
The package that had been left blocked the exit, so a security guard moved it away.
Frequent derivatives specialize the spatial or discourse relation:
- forlasi — leave or abandon a person, place, role, or cause;
- ellasi — let out, release;
- enlasi — let in, admit;
- preterlasi — omit, skip, leave out;
- postlasi — leave behind, including an estate or lasting trace.
Pro la fumo ĉiuj devis tuj forlasi la konstruaĵon.
Because of the smoke, everyone had to leave the building immediately.
La redaktoro preterlasis du ripetajn alineojn por mallongigi la artikolon.
The editor omitted two repetitive paragraphs to shorten the article.
Lasi is very frequent and neutral. Forlasi, ellasi, and enlasi are ordinary across speech and writing; preterlasi and postlasi are particularly common in edited or (formal) prose. None of these differences makes the conjugation irregular.
The status boundary matters here. Foundational norm: las-, the regular endings, and object marking are part of core Esperanto. Accepted variation: the infinitive's performer may occasionally follow the infinitive or remain implicit. Pedagogical recommendation: state it before the infinitive when ambiguity is possible, and distinguish non-prevention with lasi from active causation with igi. Attested usage: historical active-causative examples with lasi exist, but PMEG explicitly recommends avoiding that nationally influenced extension in clear modern Esperanto.
Common Mistakes
Using transitive lasi for “depart”
❌ Mi lasos je la sesa por kapti la trajnon.
Incorrect for 'I will leave at six' — no object is being left.
✅ Mi foriros je la sesa por kapti la trajnon.
I'll leave at six to catch the train.
Giving the object predicative accusative -n
❌ Lasu la pordojn malfermitajn dum la paŭzo.
Incorrect for the intended result-state reading — malfermitajn would be an attributive part of the object phrase.
✅ Lasu la pordojn malfermitaj dum la paŭzo.
Leave the doors open during the break.
Using lasi for active causation
❌ Mi lasis la teknikiston ripari mian komputilon.
Incorrect if you mean that you commissioned or caused the repair; it instead says you allowed the technician to do it.
✅ Mi riparigis mian komputilon ĉe teknikisto.
I had my computer repaired by a technician.
Translating “let's” literally
❌ Lasu nin komenci la kunvenon.
Incorrect as a neutral proposal — this asks someone to permit us to begin.
✅ Ni komencu la kunvenon.
Let's begin the meeting.
Key Takeaways
- Lasi is regular and transitive: an object remains behind, remains in a state, or is allowed to act.
- In lasi iun fari, the object of lasi is the understood subject of the infinitive.
- Use igi or a causative -igi verb for active causation, not permission.
- Use foriri for intransitive departure and ni + -u for an ordinary “let's” proposal.
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Start learning Esperanto →Related Topics
- Infinitives as ComplementsA1 — Build verb chains with an -i infinitive, assign its understood subject, and keep tense, negation, objects, and clause boundaries clear.
- Subject Control with InfinitivesA2 — Identify the understood actor of an infinitive after same-subject, influence, perception, causative, and purpose constructions.
- Objects after InfinitivesB1 — How Esperanto infinitives retain their own objects, complements, and accusative marking inside larger verb phrases.
- Predicative Complements and the AccusativeB1 — Distinguish Esperanto predicative complements from accusative objects and attributive modifiers, especially in clauses that describe an object.
- Iri: To GoA2 — Use iri with destination, route, manner, and purpose complements, and distinguish ekiri, foriri, reiri, and other motion compounds.
- -ig-: CausationB2 — Use -ig- to make something acquire a quality, enter a state, or perform an action, while tracking how causation changes verb valency.