The third conjugation — verbs whose infinitive ends in -ir — is the smallest of the three Portuguese verb classes by number of members, but do not let that fool you. It contains some of the verbs you will reach for most often: ir (to go), vir (to come), sair (to leave), dormir (to sleep), sentir (to feel), abrir (to open). The class is small but mighty, and a handful of its highest-frequency members are irregular precisely because they are used so much. This page covers the regular -ir pattern using partir as the model, and previews the predictable vowel changes that affect a subset of these verbs.
How the regular pattern works
To conjugate a regular -ir verb, drop the -ir ending to find the stem (radical), then add the ending that matches the subject and tense. The good news for English speakers: the -ir endings are almost identical to the -er endings you have already met. The differences are concentrated in just two spots in the present tense.
We will use partir (to leave, to depart) as our model verb. Its stem is part-.
Present indicative
| Subject | Ending | partir |
|---|---|---|
| eu | -o | parto |
| tu (regional) | -es | partes |
| você / ele / ela | -e | parte |
| nós | -imos | partimos |
| vocês / eles / elas | -em | partem |
O voo parte às seis da manhã, então a gente tem que sair cedo.
The flight leaves at six in the morning, so we have to leave early.
A gente parte amanhã de manhã, mal posso esperar.
We leave tomorrow morning, I can hardly wait.
Vocês partem hoje ou só na sexta?
Are you all leaving today or only on Friday?
Preterite (pretérito perfeito)
The simple past endings for regular -ir verbs are: -i, -iste, -iu, -imos, -iram. Notice that the nós form, partimos, is identical to the present tense — context tells you which one is meant.
| Subject | Ending | partir |
|---|---|---|
| eu | -i | parti |
| tu (regional) | -iste | partiste |
| você / ele / ela | -iu | partiu |
| nós | -imos | partimos |
| vocês / eles / elas | -iram | partiram |
Ela partiu sem se despedir de ninguém.
She left without saying goodbye to anyone.
Decidi ontem que vou mudar de emprego.
I decided yesterday that I'm going to change jobs.
Imperfect (pretérito imperfeito)
Here there is no surprise at all: the imperfect endings for -ir verbs are exactly the same as for -er verbs — -ia, -ias, -ia, -íamos, -iam. The two classes merge completely in this tense.
| Subject | Ending | partir |
|---|---|---|
| eu | -ia | partia |
| tu (regional) | -ias | partias |
| você / ele / ela | -ia | partia |
| nós | -íamos | partíamos |
| vocês / eles / elas | -iam | partiam |
Note the accent on partíamos: the í carries a written acute because the stress falls on it and the word would otherwise be misread. This accent is obligatory in every regular -ir and -er imperfect (comíamos, bebíamos, abríamos).
Quando eu era criança, a gente sempre dormia na casa da minha avó no fim de semana.
When I was a kid, we always slept at my grandma's house on weekends.
Common regular -ir verbs
These verbs follow the partir pattern in all the tenses above. Learn the model and they come for free.
| Infinitive | Meaning |
|---|---|
| abrir | to open |
| decidir | to decide |
| dividir | to divide, to share |
| assistir | to watch (a film, a game) |
| desistir | to give up |
| discutir | to argue, to discuss |
Você abre a janela? Tá um calor insuportável aqui dentro.
Could you open the window? It's unbearably hot in here.
A gente dividiu a conta no fim do jantar.
We split the bill at the end of dinner.
The vowel-changing -ir verbs (preview)
A subset of -ir verbs has a small twist: the stem vowel changes in the eu form of the present indicative only. The classic examples are dormir and preferir.
| Subject | dormir (to sleep) | preferir (to prefer) |
|---|---|---|
| eu | durmo | prefiro |
| tu (regional) | dormes | preferes |
| você / ele / ela | dorme | prefere |
| nós | dormimos | preferimos |
| vocês / eles / elas | dormem | preferem |
The eu form raises the stem vowel: o becomes u (dormir → durmo), and e becomes i (preferir → prefiro, sentir → sinto, vestir → visto). Every other person keeps the original vowel. This is not random — it reflects a historical sound change driven by the final -o, and it shows up only where that -o appears, i.e. the first person singular. There is no logical shortcut for which verbs are affected, but the pattern itself is consistent once you know a verb belongs to this group. The full set of rules and the complete list of affected verbs live on the stem-changing -ir verbs page.
Eu durmo muito mal quando bebo café à noite.
I sleep really badly when I drink coffee at night.
Eu prefiro ficar em casa hoje, tô cansado demais pra sair.
I'd rather stay home today, I'm way too tired to go out.
Sinto muito pela sua perda.
I'm very sorry for your loss.
Why -ir is rare but matters
By raw count, the -ir class has the fewest members of the three conjugations — Portuguese stopped coining new -ir verbs centuries ago, so the class never grew the way -ar did (almost every borrowed or invented verb today becomes an -ar verb: deletar, printar, stalkear). Yet several of the most frequent verbs in the entire language are -ir verbs, and many of them are irregular for exactly that reason — high-frequency verbs resist regularization. Ir (to go), vir (to come), sair (to go out), pedir (to ask for), ouvir (to hear), and seguir (to follow) all belong here, and none of them conjugate exactly like partir. So while you can learn the regular pattern quickly, expect to memorize the heavy hitters of this class one by one.
Common mistakes
❌ Nós partemos amanhã de manhã.
Incorrect — this uses the -er ending; -ir verbs take -imos for nós.
✅ Nós partimos amanhã de manhã.
We leave tomorrow morning.
❌ Eu dormo até tarde no domingo.
Incorrect — dormir raises the stem vowel in the eu form.
✅ Eu durmo até tarde no domingo.
I sleep in late on Sunday.
❌ Eu prefero chá a café.
Incorrect — preferir raises e to i in the eu form.
✅ Eu prefiro chá a café.
I prefer tea to coffee.
❌ Quando eu era criança, eu dormia muito, mas meus irmãos dormam pouco.
Incorrect — the imperfect of dormir is regular: dormiam, not 'dormam'.
✅ Quando eu era criança, eu dormia muito, mas meus irmãos dormiam pouco.
When I was a kid, I slept a lot, but my siblings slept little.
The recurring English-speaker trap is treating -er and -ir verbs as interchangeable. They are nearly identical, which makes the one real difference — partimos vs. comemos — easy to overlook. Lock in the -imos ending and the rest takes care of itself.
Key takeaways
- Regular -ir present endings: -o, -es, -e, -imos, -em. The only oddity is nós -imos (not -emos).
- The preterite (-i, -iste, -iu, -imos, -iram) and imperfect (-ia, -ias, -ia, -íamos, -iam) are predictable; the imperfect is identical to -er verbs.
- A subset of -ir verbs raises the stem vowel in the eu form only: durmo, prefiro, sinto, visto.
- The class is small, but it holds many of the most-used verbs in the language — most of which are irregular and worth learning individually.
Now practice Portuguese
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Start learning Portuguese→Related Topics
- First Conjugation: -ar VerbsA1 — The largest and most regular Brazilian Portuguese verb class — endings across the main tenses, high-frequency verbs, and the gostar de trap.
- Second Conjugation: -er VerbsA1 — The Brazilian Portuguese -er class — regular endings modeled on comer, why so many -er verbs are irregular, and how the imperfect merges -er with -ir.
- The Three Conjugation Classes (-ar, -er, -ir)A1 — How Brazilian Portuguese sorts every verb into three classes by infinitive ending, and what that tells you about its conjugation.
- Stem-Changing -ir VerbsA2 — The predictable e→i and o→u vowel shift in the eu form of many Brazilian Portuguese -ir verbs, and why it reappears throughout the subjunctive.
- Subject Pronouns with VerbsA1 — The Brazilian Portuguese subject pronouns — including the everyday 'a gente', the regional 'tu', and why Brazilians drop 'vós' but keep pronouns more than other pro-drop languages.