Irregular verbs

Portuguese conjugation is, in essence, regular: given the infinitive, the thematic vowel and the model of the conjugation, more than fifty forms follow by analogy. Irregular verbs are those for which this deduction fails — because the stem changes, because the endings are not the expected ones, or both. They are few, but they include the most heavily used verbs in the language, which is why their irregularity is at once so conspicuous and so unavoidable to learn.

What makes a verb irregular

A verb is called irregular when one of its forms departs from the paradigm of the model verb of its conjugation (amar, vender, partir). Two kinds of departure are worth distinguishing:

• systematic irregularities, which follow a rule of their own and affect whole groups of verbs (the stem alternations, the spelling shifts of ficar → fiquei or começar → comecei);
• lexical irregularities, idiosyncratic, that must be memorised verb by verb (ser, ir, fazer, pôr).

Most irregularity is concentrated at two points of the paradigm: the first person of the present indicative (faço, digo, peço), from which the whole present subjunctive and the imperative derive, and the preterite, from which the pluperfect, the imperfect subjunctive and the future subjunctive derive.

The strong preterites

The most coherent irregular group is that of the strong preterites (pretéritos fortes). In regular verbs the stress of the preterite falls on the ending — cantei, cantou, vendi, vendeu. In the strong ones, inherited from root-stressed Latin perfects, the stress retreats to the stem in the first and third persons singular:

eu	fiz
tu	fizeste
ele/ela	fez
nós	fizemos
vós	fizestes
eles/elas	fizeram

Note fiz and fez, stressed on the stem and without the regular thematic vowel. This same mould — descended from Latin forms such as FĒCĪ (fazer), DĪXĪ (dizer), HABUĪ (haver), POTUĪ (poder), SAPUĪ (saber) and TENUĪ (ter) — accounts for whole families: disse, trouxe, quis, soube, coube, houve, pôs, pôde, teve, esteve, veio.

Suppletion: ser and ir

The extreme case of irregularity is suppletion: when a verb’s paradigm gathers forms from etymologically distinct roots. In Portuguese, ser (to be) and ir (to go) share, in the preterite, exactly the same forms — fui, foste, foi, fomos, fostes, foram — inherited from the perfect of Latin esse. Only context resolves the ambiguity:

Ser further gathers forms of yet another origin in the present (sou, és, é) and the imperfect (era), which makes it the most irregular verb in the language.

Stem alternations

Many third-conjugation verbs have a stem e or o that alternates regularly depending on whether the syllable is stressed or unstressed. In the first person of the present indicative the e rises to i and the o rises to u; in the other stressed persons the mid timbre returns. This is a predictable, not a lexical, irregularity:

Infinitive	Eu (present)	Tu (present)
servir (to serve)	sirvo	serves
dormir (to sleep)	durmo	dormes
preferir (to prefer)	prefiro	preferes
subir (to go up)	subo	sobes

To these belong the purely orthographic changes, which keep the sound of the stem intact: c → qu (ficar → fiquei), g → gu (chegar → cheguei), ç → c (começar → comecei), g → j (proteger → protejo).

The high-frequency irregulars

A handful of verbs concentrate the least predictable irregularity — and they are, not by chance, the most frequent. They are best known by heart:

Infinitive	Present (eu)	Preterite (ele)
ser (to be)	sou	foi
estar (to be)	estou	esteve
ter (to have)	tenho	teve
haver (there to be)	hei	houve
ir (to go)	vou	foi
vir (to come)	venho	veio
ver (to see)	vejo	viu
dar (to give)	dou	deu
fazer (to do)	faço	fez
dizer (to say)	digo	disse
trazer (to bring)	trago	trouxe
pôr (to put)	ponho	pôs
poder (can)	posso	pôde
querer (to want)	quero	quis
saber (to know)	sei	soube

Note that vir and ver cross over treacherously: vimos is at once the present of vir and the preterite of ver, and only the sentence separates nós vimos do Porto (“we come from Porto”, vir) from ontem vimos o filme (“yesterday we saw the film”, ver).

Double participles and defective verbs

Some verbs are abundant: they have two participles, a regular one (used in the compound tenses, with ter) and an irregular, shorter one (used adjectivally and in the passive, with ser or estar) — tinha aceitado but a proposta foi aceite (“the proposal was accepted”); tinha entregado but o trabalho está entregue (“the work is handed in”). Others are defective, lacking certain forms: abolir and falir avoid the first person of the present, and reaver (“to recover”) is conjugated only where haver keeps its v (reavemos, reouve).

Learning the irregulars

The most effective strategy is not to memorise scattered lists, but to fix the points of radiation: the first person of the present, from which the whole subjunctive springs, and the third person of the preterite, from which the past tenses spring. Master these two pivots in the fifteen verbs of the table above and almost all of Portuguese irregularity comes within reach — because the rest of the conjugation, even in them, still obeys the system.