Esperanto -ig- and -iĝ-: transitive vs intransitive verbs

Every Esperanto verb either takes a direct object (transitive) or does not (intransitive), and the suffixes -ig- and -iĝ- switch between the two. -Ig- adds a doer and an object: sidi – "to sit" → sidigi – "to seat (someone)". -Iĝ- removes the object: fermi – "to close (something)" → fermiĝi – "to close (by itself)". Both are official suffixes from the 1905 Fundamento.

English hides the difference, because "open", "start", "change" and "break" work both ways: "I opened the door" and "the door opened". Esperanto needs two forms: Mi malfermis la pordon. and La pordo malfermiĝis. A bare La pordo malfermis is an error.

With -iĝ- the object becomes the subject; with -ig- the subject becomes the object:

Mi subject malfermis verb la pordon object

I opened the door.

La pordo subject malfermiĝis verb

The door opened.

La infano subject dormas verb

The child is sleeping.

Ŝi subject dormigas verb la infanon object

She is putting the child to sleep.

#Transitive or intransitive?

A transitive verb can have a direct object, which takes -n (see the accusative). Ask "whom?" or "what?" after the verb. Mi fermas la pordon – "I close the door": the answer is la pordon, so fermi is transitive. Mi dormas – "I sleep" has no answer, so dormi is intransitive.

A plain verb root gives no sign of which kind it is; it depends on meaning, and dictionaries record it. ReVo, the free Esperanto dictionary, marks most verbs tr (transitive), ntr (intransitive) or x (both). Every root verb in the tables below was checked there, and its label is shown.

Some verbs go both ways. ReVo marks paroli with x: Ŝi parolas. – "She is speaking." and Ŝi parolas Esperanton. – "She speaks Esperanto." A few intransitive verbs accept an object that only repeats the action: Mi dancis valson. – "I danced a waltz."

#Transitive roots: -iĝ- removes the object

Add -iĝ- when the object becomes the subject and the action happens by itself, or nobody cares who did it. Compare:

• La infano rompis la glason. – "The child broke the glass."
• La glaso rompiĝis. – "The glass broke."

#Intransitive roots: -ig- adds an object

Add -ig- to say that someone or something makes the action happen. The old subject becomes the object: La infano dormas. → Ŝi dormigas la infanon. – "She is putting the child to sleep." Every -ig- verb takes an object (PMEG).

Roots that already take an object can add -ig- too, meaning "make someone do it": kompreni – "to understand" → komprenigi – "to make understand"; manĝi – "to eat" → manĝigi – "to feed"; scii – "to know" → sciigi – "to inform". The object is either the person or the thing, never both: Mi sciigis lin pri la afero. – "I informed him about the matter."

#Sidi, sidiĝi, sidigi: three verbs from one root

With an intransitive root, both suffixes can attach.

After an intransitive root, -iĝ- marks the start of the action, almost like the prefix ek- (see prefixes): sidiĝi ≈ eksidi. Sidiĝi names the movement into the seat, sidi the position: Bonvolu sidiĝi. – "Please sit down."

#Adjective and noun roots: both suffixes

From an adjective, -ig- means "make it that" and -iĝ- means "become that": pura – "clean" → purigi – "to clean", puriĝi – "to get clean". Nouns follow the same pattern; see word-building for the logic.

For a couple, use geedziĝi: Ili geedziĝis en Majo. – "They got married in May." With amiko – "friend" the useful verb is amikiĝi: Mi amikiĝis kun ŝi. – "I became friends with her."

#Mistakes English speakers make

The usual error is to use a transitive verb with no object. If there is no object and the thing simply happens, you probably need -iĝ-.

Komenci with an infinitive is correct, because the infinitive is the object: Komencis pluvi. – "It began to rain."

#Esti fermita or fermiĝi?

Both can describe a shut door, but they say different things.

A passive always has a doer behind it, who can be added with de: La pordo estis fermita de la gardisto. An -iĝ- verb says the action happens more or less by itself, so a doer is normally not named. PMEG contrasts Li estis naskita en Januaro, which stresses the act of birth, with Li naskiĝis en Januaro, which stresses the newborn. Likewise Li estas nomata Petro means people call him that, while Li nomiĝas Petro just gives his name. More on the passive: participles.

#When no suffix is needed

• A verb that already means a change usually needs no -iĝ-. Morti already means "to pass from life to death"; mortiĝi is rare and suggests an accident (PMEG).
• PMEG prefers ĉesi or ekĉesi to ĉesiĝi, ektimi to timiĝi, and ekscii to sciiĝi.
• To say that someone makes something happen that is already an -iĝ- verb, use igi with an infinitive instead of stacking suffixes: La bruo igis ŝin vekiĝi. – "The noise made her wake up." Igi – "to cause" and iĝi – "to become" are also verbs on their own.

#Examples in sentences

• Mi fermis la pordon. – "I closed the door."
• La pordo fermiĝis pro la vento. – "The door closed because of the wind."
• La orkestro komencis la koncerton akurate. – "The orchestra started the concert on time."
• La koncerto komenciĝis je la oka. – "The concert began at eight."
• La infano sidiĝis apud la fenestro. – "The child sat down by the window."
• La patro sidigis la bebon sur la seĝon. – "The father sat the baby down on the chair."
• La akvo jam bolas. – "The water is already boiling."
• Mi boligas akvon por teo. – "I'm boiling water for tea."
• Liaj vortoj ĝojigis ĉiujn. – "His words made everyone happy."
• La prezoj altiĝis dum la jaro. – "Prices went up during the year."

#Common questions

#What is the difference between -ig- and -iĝ-?

-Ig- means "to cause": it adds a doer and an object (bruli → bruligi). -Iĝ- means "to become" or "to happen by itself": it never takes an object (fermi → fermiĝi). All the suffixes are listed on suffixes.

#Is komenci transitive in Esperanto?

Yes, ReVo marks it tr. It takes the thing begun (Mi komencis la laboron) or an infinitive (Li komencis paroli). For an event that starts by itself, use komenciĝi: La koncerto komenciĝis.

#How do you say "the shop opens at nine"?

La butiko malfermiĝas je la naŭa. If a person does the opening, use the plain verb: La vendisto malfermas la butikon je la naŭa.

#How can I tell if an Esperanto verb is transitive?

Check ReVo, which marks verbs tr, ntr or x (both), or ask "whom?" or "what?" after the verb. Verbs ending in -ig- are always transitive and verbs ending in -iĝ- never are.

#How do I type -iĝ- without the hat letter?

In the x-system write igx: komencigxi becomes komenciĝi.

#Is it sidi or sidiĝi for "to sit down"?

Sidiĝi names the act of sitting down: Ŝi sidiĝis apud mi. – "She sat down next to me." Sidi is the state of being seated: Mi sidas. – "I am sitting." Sidigi means to seat someone else.

#Sources

• PMEG: IG-verboj, IĜ-verboj, Objektaj verboj, Senobjektaj verboj
• PMEG: IG and IĜ (including the comparison of IĜ-verbs with passive verbs)
• PMEG: Pasivo – bazaj reguloj, Pasivigeblaj frazoj
• Reta Vortaro (ReVo): abbreviations tr, ntr, x; entries such as komenci, fini, fermi, sidi, morti, veki, bruli
• Fundamento de Esperanto – Akademio de Esperanto