Verb Classes: Overview of Irregular Patterns

Portuguese has a reputation for being a language of irregular verbs. Open a conjugation reference and you see hundreds of verbs labeled "irregular," each with its own full paradigm. The reputation is misleading. Most so-called irregular verbs are not unique — they share patterns with other verbs, and once you learn the pattern, the individual verbs become transparent. A small number of verbs are genuinely one-off irregulars (ser, estar, ter, ir, vir, pôr, fazer, dizer, ver, poder, saber, querer, trazer, haver), and these deserve memorization. Everything else falls into a handful of recognizable classes.

This page is the map. It surveys the major verb classes — spelling-change, stem-change, -ear, -iar, -air — and gives the short list of truly irregular verbs at the end. Dedicated pages drill each class in detail; this overview is where you come to get oriented.

The big picture

Portuguese verbs divide into three conjugation classes based on their infinitive ending: -ar (falar, dançar, cantar), -er (comer, beber, vender), and -ir (partir, abrir, dormir). The AR, ER, IR verbs page covers the regular paradigms. Most of the "irregular" patterns on this page are actually sub-classes within the three main conjugations — rule-governed deviations from the regular template, not random exceptions.

The patterns break down into two broad types:

1. Spelling changes — the pronunciation is regular, but the spelling shifts to preserve that pronunciation when vowels change. These are not irregularities at all; they are forced by Portuguese orthography. Covered in depth on the spelling changes page.

2. Stem changes — the stem vowel genuinely changes in some forms. These are phonological patterns, and they cluster in predictable places (especially the 1sg present indicative and the entire present subjunctive). Covered on the stem changes page.

Below, both are surveyed together so you can see them as one landscape.

Spelling-change classes

Spelling changes affect a consonant at the end of the stem when the following vowel changes. The goal is always to preserve the original sound of the infinitive. Five patterns cover virtually all cases.

-car verbs: c → qu before e/i

The /k/ sound of the infinitive must stay /k/ even when the following vowel becomes e or i. Since plain c before e/i would be read /s/, Portuguese writes qu.

Affected forms: preterite 1sg (ficar → fiquei) and the entire present subjunctive (fique, fiques, fique, fiquemos, fiquem).

Common -car verbs: ficar, tocar, explicar, brincar, aplicar, indicar, comunicar, praticar, publicar, atacar, educar.

-gar verbs: g → gu before e/i

The hard /g/ sound must be preserved. Plain g before e/i would become /ʒ/ (soft g), so Portuguese writes gu.

Affected forms: same as -car — preterite 1sg (cheguei, paguei, joguei) and present subjunctive (chegue, pague, jogue).

Common -gar verbs: chegar, pagar, jogar, entregar, apagar, investigar, obrigar, carregar, afogar, navegar.

-çar verbs: ç → c before e/i

The /s/ sound is marked with ç before a, o, u and with plain c before e, i. So when the vowel changes from a (in the infinitive) to e (in a conjugated form), the cedilla simply drops.

Affected forms: preterite 1sg (comecei, dancei, almocei) and present subjunctive (comece, dance, almoce).

Common -çar verbs: começar, dançar, almoçar, abraçar, lançar, alcançar, avançar, reforçar.

-ger / -gir verbs: g → j before o/a

In -ger and -gir verbs, the infinitive has a soft /ʒ/ sound (the "g" before e or i). When a conjugation ending brings an o or a after the stem, plain g would become hard /g/ — so Portuguese writes j, which is always /ʒ/.

Affected forms: present indicative 1sg (protejo, dirijo, fugir → fujo) and the entire present subjunctive (proteja, dirija).

Common -ger verbs: proteger, eleger, reger, emergir, convergir. Common -gir verbs: dirigir, fingir, exigir, corrigir, afligir, mugir.

-guer / -guir verbs: gu → g before o/a

When gu (representing /g/) meets a conjugation ending starting with o or a, the u is superfluous — plain g before o/a already sounds /g/. So the u drops.

Affected forms: present indicative 1sg (sigo, consigo, ergo) and present subjunctive (siga, consiga, erga).

Common -guir/-guer verbs: seguir, conseguir, perseguir, prosseguir, distinguir, erguer.

Note that seguir also undergoes the e→i stem change — so the 1sg sigo reflects both the vowel change (e→i) and the spelling change (gu→g). Verbs like erguer and distinguir show only the spelling change.

Stem-change classes

Stem changes are genuine vowel alternations inside the stem — the pronunciation changes, not just the spelling. They cluster in predictable positions and follow a handful of patterns.

E → I in -ir verbs (1sg present, whole subjunctive)

Certain -ir verbs change their stem e to i in the 1sg present indicative and throughout the present subjunctive. The other present indicative forms keep e.

O → U in -ir verbs (1sg present, whole subjunctive)

A parallel pattern: certain -ir verbs change o to u in the 1sg present indicative and the present subjunctive.

The inverse pattern: u ↔ o (subir, fugir, sacudir)

Three verbs — subir ("to go up"), fugir ("to flee"), and sacudir ("to shake") — follow the inverse pattern. The infinitive already has u, the 1sg keeps u, but the stressed non-1sg forms (tu, ele, eles) shift to o.

Notice that fugir also shows the spelling change g → j (fujo not fugo) — so it combines two pattern types.

-ear verbs: add -i- before e

Verbs ending in -ear insert an i before the ending whenever the stress falls on the stem (the 1sg, 2sg, 3sg, and 3pl of the present indicative, and the corresponding subjunctive forms).

Common -ear verbs: passear, recear, nomear, cear, pentear, rodear, semear, bloquear, folhear.

-iar verbs: two patterns

Verbs ending in -iar split into two groups.

Pattern A: -iar with -ei- (like -ear verbs). A small set of -iar verbs behaves exactly like -ear verbs: stressed stem forms insert an e before the i, yielding -ei-. Memorize this list as ARMIO (or any other mnemonic): ansiar, remediar, mediar, incendiar, odiar (and a few less common ones like intermediar, premiar).

Pattern B: regular -iar. Most -iar verbs are regular — no stem change, no inserted vowel. The i of the stem stays the i of the stem.

Common regular -iar verbs: confiar, desafiar, copiar, enviar, variar, criar, aliviar, abreviar, negociar, pronunciar, iniciar.

-air verbs: stem i → stressed forms

Verbs ending in -air (sair, cair, trair) have a stem ending in a vowel (-a-) followed by -ir. In the present indicative, the 1sg inserts a glide (saio, caio, traio), and the 1pl and 2pl carry a written accent (saímos, saís) to mark the separation of the vowels. The pattern is distinctive enough that -air verbs deserve to be recognized as a small class of their own.

Note the written accent on saímos, caímos, traímos (1pl) — the stress falls on the -í-, and the accent disambiguates from the diphthong -ai-. The past forms also show this accent pattern.

Closed ↔ open vowel alternation in -er verbs

Several regular-looking -er verbs show a pronunciation alternation that is largely invisible in writing: a closed [e] or [o] in the infinitive and 1pl forms, opening to [ɛ] or [ɔ] in the stressed non-1pl forms. Spelling does not mark this change, but native pronunciation does.

Poder is additionally irregular (the 1sg posso, the preterite pude), so it shows up on the list of truly irregular verbs below.

This closed/open alternation is phonological, not orthographic. Learners often miss it because the spelling does not signal the change. Listening to native speakers pronounce these forms is the best way to internalize it.

Truly irregular verbs

Some verbs do not fit any regular pattern. Their forms have to be learned directly, tense by tense. The following list is essentially complete for the high-frequency irregulars of European Portuguese:

Each of these has a dedicated page in the grammar reference (see the present indicative and preterite irregular pages). The key insight is that this list is short. Fifteen verbs plus their compounds (manter, obter, conter, propor, compor, desfazer, predizer, rever, etc.) account for virtually all the genuinely irregular forms you will meet.

How to study verb classes

A practical approach:

1. Learn the regular -ar, -er, -ir paradigms first. These are the baseline. Everything else is a deviation from them.

2. Learn the five spelling-change classes. These are 100% predictable, so a single hour of focused practice pays off across hundreds of verbs.

3. Learn the -ir stem changes (e→i and o→u). Master sentir, dormir, servir, vestir, mentir and you have covered the high-frequency cases.

4. Note the -ear verbs and the -iar "ARMIO" set. Small but visible — you will encounter passear, odiar, ansiar regularly.

5. Memorize the short list of truly irregular verbs. These are high-frequency, so repetition happens naturally.

Portuguese "irregularity" stops looking scary once you see the patterns. Most of what is labeled irregular is just spelling or phonological adjustment. The truly unique verbs are a small, learnable set.

Comparison with Spanish

Spanish has similar spelling-change classes (-car, -gar, -zar with c→qu, g→gu, z→c before e/i) and similar stem-change classes (e→ie, o→ue). The overall structure is parallel, though the specific patterns differ:

• Portuguese has no e→ie or o→ue diphthongization. Spanish tengo, tienes has no Portuguese equivalent — Portuguese stays tenho, tens without diphthong.
• Portuguese has the distinctive -ear insertion pattern (passeio) that Spanish does not have.
• Portuguese has the -iar ARMIO set (odeio); Spanish has a similar odio, odias but without the -ei- insertion.
• Portuguese -air verbs (saio, cais, sai) have no close Spanish analog.

If you have studied Spanish, the spelling-change classes transfer almost directly. The stem-change classes are slightly different — Portuguese is less exuberant with diphthongization.

Comparison with English

English has almost no morphological verb classes in the present tense — I run, you run, he runs is the only alternation, and that is just the 3sg -s. Portuguese packs person, number, tense, and mood into its verb endings, which means the "class" a verb belongs to matters enormously. An English speaker has to get used to the idea that the same verb conjugation might look different in different persons because of spelling or phonological adjustments that English simply does not have.

The good news: once you see these classes as patterns rather than exceptions, Portuguese verbs become much more predictable than they initially appear.

Common Mistakes

Spelling-change verbs are not optional. The qu before e is required by Portuguese orthography.

Sentir (to feel) has the e→i stem change: sinto, sentes, sente, sentimos, sentem. Do not confuse it with sentar (to sit), which is a different verb entirely.

The 1sg of dormir is durmo, not dormo. This is one of the most frequent stem-change errors for learners coming from Spanish (where duermo is the form).

Subir, fugir, sacudir follow the inverse pattern: the 1sg keeps the u of the infinitive, but the stressed non-1sg forms shift to o.

Odiar, ansiar, remediar, mediar, incendiar all insert -ei- in stressed-stem forms. Odeio, anseio, remedeio.

Key takeaways

• Most "irregular" Portuguese verbs belong to regular sub-classes. The truly unique irregulars are a short list of about 15 verbs.
• Spelling-change classes (-car, -gar, -çar, -ger/-gir, -guer/-guir) adjust consonants to preserve pronunciation. 100% predictable from the infinitive ending.
• Stem-change classes in -ir verbs (e→i, o→u) affect the 1sg present and the full present subjunctive. Three verbs (subir, fugir, sacudir) follow the inverse u↔o pattern.
• -ear verbs insert -i- before stressed endings (passeio, receio).
• -iar verbs split: a small "ARMIO" set inserts -ei- (odeio, anseio); all others are regular (confio, estudo, envio).
• -air verbs show saio, cais, sai, saímos, saem — written accent on the 1pl.
• Truly irregular verbs: ser, estar, ter, ir, vir, pôr, fazer, dizer, ver, poder, saber, querer, trazer, haver, dar. Their compounds (manter, propor, desfazer) inherit the irregularity.
• Dedicated pages drill each class; this page is the map.