Irregular Verb Groups | Portuguese (Brazil) Grammar

Brazilian Portuguese irregularity looks chaotic at first, but it isn't random. Almost every "irregular" verb falls into one of five recognizable groups, and the irregularity is concentrated in just a couple of slots in the conjugation. This page gives you the map.

The big insight: irregularity lives in two slots

Here is the single most useful fact about BR verbs. Most irregularity is concentrated in exactly two places:

The first-person singular present indicative (the eu form), and
The preterite stem (the past completed-action stem).

If you learn those two slots for an irregular verb, the rest of the conjugation usually falls out predictably — the present subjunctive is built from the eu present, and the imperfect, pluperfect, and past subjunctive are built from the preterite stem. Get the eu form and the preterite, and you have covered roughly 90% of a verb's irregularity. This is why we organize by type of irregularity rather than by individual verb.

💡

When you meet a new irregular verb, ask two questions: "What is the eu present form?" and "What is the ele preterite form?" Those two answers predict almost everything else.

Group 1: Suppletive verbs (different stems)

Suppletion means a single verb pulls forms from what were originally different verbs in Latin. The result is a paradigm that switches stems with no warning. English does this too — go / went / gone mixes two unrelated roots.

The headline case in BR is ir (to go) and ser (to be), which share the same preterite:

Form	ser	ir
eu (present)	sou	vou
eu (preterite)	fui	fui
ele (preterite)	foi	foi
nós (preterite)	fomos	fomos

Yes — fui can mean both "I was" and "I went." Context always disambiguates, and Brazilians never find it confusing.

Ontem eu fui ao mercado.

Yesterday I went to the market. (ir)

A festa foi ótima, todo mundo adorou.

The party was great, everyone loved it. (ser)

The other major suppletive verb is pôr (to put), whose forms barely resemble the infinitive: ponho (I put), põe (he/she puts), pus (I put, past), punha (I used to put). Note the circumflex on the infinitive pôr — it distinguishes the verb from the preposition por (by, for).

Eu ponho açúcar no café, e você?

I put sugar in my coffee — and you?

Group 2: -g- insertion in the eu form

A large family of verbs inserts a -g- (or -ç-, the soft equivalent) in the eu present form only. The rest of the present tense is regular. This is the most learnable group because the pattern is so consistent.

Infinitive	Meaning	eu form
fazer	to do/make	faço
dizer	to say	digo
trazer	to bring	trago
ouvir	to hear	ouço
valer	to be worth	valho
pedir	to ask for	peço
perder	to lose	perco

Because the present subjunctive is built from the eu form, this -g-/-ç- carries through the whole subjunctive: faço → que eu faça, digo → que eu diga, ouço → que eu ouça. That is the payoff of learning the eu form well.

Eu faço o jantar e você lava a louça, combinado?

I'll make dinner and you wash the dishes, deal?

Eu trago a sobremesa, não se preocupe.

I'll bring dessert, don't worry.

Eu não ouço nada com essa música tão alta.

I can't hear anything with the music so loud.

Group 3: Stem-vowel changes

In many -ir verbs, the stressed stem vowel shifts in the eu form (and, by extension, through the subjunctive). The most common pattern raises e → i or o → u.

Infinitive	Meaning	eu form	ele form
dormir	to sleep	durmo	dorme
preferir	to prefer	prefiro	prefere
servir	to serve	sirvo	serve
sentir	to feel	sinto	sente
mentir	to lie	minto	mente

Note the asymmetry: the vowel changes in the eu form (durmo, prefiro) but reverts in the ele form (dorme, prefere). English speakers, who don't change stem vowels in the present, tend to over-regularize and say "dormo" — resist that.

The verb subir (to go up) is a famous mixed case: the eu form keeps the u (subo) but the ele form raises to o (sobe). So you get eu subo but ele sobe — different vowels in the same present tense.

Eu durmo melhor com a janela aberta.

I sleep better with the window open.

Eu prefiro ir de manhã, evita o trânsito.

I prefer to go in the morning, it avoids the traffic.

Eu subo de escada, o elevador está quebrado.

I'll go up by the stairs, the elevator is broken.

💡

Stem-vowel changes affect only the stressed stem syllable. That's why the nós form (where stress falls on the ending) keeps the original vowel: dormimos, preferimos, servimos — not "durmimos." The vowel only shifts when the stem itself is stressed.

Group 4: Spelling changes only (no sound change)

This group is not really irregular at all — the pronunciation is perfectly regular, but Portuguese spelling rules force a letter change to keep the sound consistent. These appear mostly in the preterite eu form of -car, -gar, and -çar verbs.

Infinitive	Meaning	eu preterite	Why
ficar	to stay	fiquei	c → qu keeps the hard "k" before e
chegar	to arrive	cheguei	g → gu keeps the hard "g" before e
começar	to begin	comecei	ç → c, since c is already soft before e
almoçar	to have lunch	almocei	ç → c before e

Think of these as "honest" verbs: they bend the spelling precisely so the sound won't change. An English parallel is picnic → picnicked (adding the k to keep the hard "c").

Eu cheguei atrasado, desculpa.

I arrived late, sorry.

Fiquei em casa o fim de semana inteiro.

I stayed home the whole weekend.

Comecei a estudar português esse ano.

I started studying Portuguese this year.

Group 5: Contracted future and conditional stems

A few very common verbs use a shortened stem in the simple future and the conditional. Instead of building on the full infinitive (the normal rule), they drop a syllable.

Infinitive	Future stem	Example (future)	Example (conditional)
fazer	far-	farei (I will do)	faria (I would do)
dizer	dir-	direi (I will say)	diria (I would say)
trazer	trar-	trarei (I will bring)	traria (I would bring)

So it's farei, not "fazerei"; direi, not "dizerei". In everyday BR speech the simple future is mostly replaced by ir + infinitive (vou fazer), so you will hear these contracted futures more in writing and formal registers (formal). The conditional forms (faria, diria, traria), however, stay common in speech because they soften requests and express hypotheticals.

Eu faria qualquer coisa por essa vista.

I'd do anything for this view. (conditional, common)

O presidente dirá amanhã se aceita o cargo.

The president will say tomorrow whether he accepts the post. (future, formal/written)

Common Mistakes

❌ Eu dormo cedo durante a semana.

Incorrect — dormir raises o→u in the eu form: durmo.

✅ Eu durmo cedo durante a semana.

I sleep early during the week.

❌ Eu fazerei isso amanhã.

Incorrect — fazer uses the contracted future stem: farei.

✅ Eu farei isso amanhã.

I'll do that tomorrow.

❌ Eu chegei tarde ontem.

Incorrect — chegar needs g→gu before e: cheguei.

✅ Eu cheguei tarde ontem.

I arrived late yesterday.

❌ Eu dizo que sim.

Incorrect — dizer inserts -g- in the eu form: digo.

✅ Eu digo que sim.

I say yes.

❌ É importante que eu faço isso.

Incorrect — the subjunctive is built from the eu form faço, giving faça.

✅ É importante que eu faça isso.

It's important that I do this.

Key Takeaways

Irregularity clusters in the eu present and the preterite stem — learn those two and the rest follows.
The five groups are: suppletion (ir/ser/pôr), -g-/-ç- insertion (faço, digo, ouço), stem-vowel change (durmo, prefiro), spelling-only (fiquei, cheguei), and contracted future/conditional (far-, dir-, trar-).
Spelling-only changes are not real irregularities — they keep the sound regular.
For the full present-tense picture, see the all-irregulars summary.

Now practice Portuguese

Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.

Start learning Portuguese→