# Spanish irregular verbs

Spanish verbs are a complex area of Spanish grammar, with many combinations of tenses, aspects and moods (up to fifty conjugated forms per verb). Although conjugation rules are relatively straightforward, a large number of verbs are irregular. Among these, some fall into more-or-less defined deviant patterns, whereas others are uniquely irregular. This article summarizes the common irregular patterns.
As in all Romance languages, many irregularities in Spanish verbs can be retraced to Latin grammar.

## Orthographic changes

Due to the rules of Spanish orthography, some predictable changes are needed to keep the same consonant sound before a or o and e or i, but these are not usually considered irregularities. The following examples use the first person plural of the present subjunctive:
* /k/: c—qu: tocar > toquemos (-car), delinquir > delincamos (-quir).
* /θ/: z—c: gozar > gocemos (-zar), vencer > venzamos (-cer).
* /x/: g—j: proteger > protejamos (-ger). But in verbs ending in -jar, the j is kept before e: mojar > mojemos (not *mogemos).
* /ɡ/: g—gu: negar > neguemos (-gar), distinguir > distingamos (-guir).
* /ɡw/: gu—gü: averiguar > averigüemos (-guar).
Other predictable changes involve stress marks, i—y alternations and i-dropping, some of which are sometimes considered as irregularities. These examples are several forms of otherwise regular preterites:
* Stress mark on stressed i after a, e or o: caer > caímos (-caer), leer > leímos (-eer), oír > oímos (-ír, -oír); this does not apply to any G-verbs such as traer and its related forms.
* Stress mark not used in monosyllabic forms: liar > lie /lje/, lio /ljo/; ver > vi, vio. However, before 2010, the forms lié /liˈe/ and lió /liˈo/, fié and fió, guié and guió, and crié and crió could also be written with the accent mark by writers who pronounce these forms as bisyllabic. But this option was not available for vio.
* Unstressed i is written y between non-silent vowels: caer > cayó, cayeron (-aer, -caer); construir > construyó, construyeron (-uir). This does not apply to verbs ending in -quir (for example, delinquir > delinquió, delinquieron).
* Unstressed i is dropped between ll or ñ and a vowel: bullir > bulló (not *bullió) (-llir/-ñir), tañer > tañó (-ñer).

## Stem-vowel changes

There are two kinds of changes that can affect stem vowels of some Spanish verbs: diphthongization and vowel raising. Both changes affect -e- or -o- in the last (or only) syllable of a verb stem. Diphthongization changes -e- to -ie-, and -o- to -ue-. Vowel raising changes the mid vowels -e- and -o- to the corresponding high vowels: -i- and -u- respectively. Some verbs, in their various forms, can exhibit both kinds of changes (e.g. sentir, siente, sintió (e-ie-i); dormir, duerme, durmió) (o-ue-u).

### Diphthongization

Some verbs with -e- or -o- in their stem are inherently diphthongizing, whereas others are not: their identities must be learned individually.
In a diphthongizing verb, the change turns -e- into -ie- and -o- into -ue- when the syllable in question is stressed, which in effect happens only in the singular persons and third-person plural of the present indicative and present subjunctive, and in the imperative (all other tenses and forms are stressed on their endings, not their stems). The dictionary form always has the vowel, not the diphthong, because, in the infinitive form, the stress is on the ending, not the stem. Exceptionally, the -u- of jugar (u-ue -gar, -jugar) and the -i- of adquirir and inquirir (i-ie) also are subject to diphthongization (juega, etc.; adquiere, etc.).
In word-initial position, *ie- is written ye- (errar > yerro) (e-ie > ye) and *ue- is written hue- (oler > huele) (o-ue > hue, oler). Also, the -ue- diphthong is written -üe- after g, with the diaeresis to indicate that the letter is not silent (avergonzarse > me avergüenzo) (reflexive, go-güe -zar).
The following examples show that all three conjugations (-ar, -er, and -ir verbs) include some diphthongizing verbs (only some tenses and persons are shown, for contrasting purposes):

#### Present indicative

| Verbs | yo | tú | vos | él, ella, usted | nosotros, nosotras | vosotros, vosotras | ellos, ellas, ustedes |
| pensar | pienso | piensas | pensás | piensa | pensamos | pensáis | piensan |
| contar | cuento | cuentas | contás | cuenta | contamos | contáis | cuentan |
| perder | pierdo | pierdes | perdés | pierde | perdemos | perdéis | pierden |
| moler | muelo | mueles | molés | muele | molemos | moléis | muelen |
| oler | huelo | hueles | olés | huele | olemos | oléis | huelen |
| sentir | siento | sientes | sentís | siente | sentimos | sentís | sienten |
| dormir | duermo | duermes | dormís | duerme | dormimos | dormís | duermen |

#### Present subjunctive

| Verbs | yo | tú | vos (*) | él ella usted | nosotros nosotras | vosotros vosotras | ellos ellas ustedes |
| pensar | piense | pienses | pienses / pensés | piense | pensemos | penséis | piensen |
| contar | cuente | cuentes | cuentes / contés | cuente | contemos | contéis | cuenten |
| perder | pierda | pierdas | pierdas / perdás | pierda | perdamos | perdáis | pierdan |
| moler | muela | muelas | muelas / molás | muela | molamos | moláis | muelan |
| oler | huela | huelas | huelas / olás | huela | olamos | oláis | huelan |
| sentir | sienta | sientas | sientas / sintás | sienta | sintamos | sintáis | sientan |
| dormir | duerma | duermas | duermas / durmás | duerma | durmamos | durmáis | duerman |
(*) In Central America pensés, contés, etc. are used, but Spanish Royal Academy prescribes pienses, cuentes, etc., according to Rioplatense Spanish.

#### Imperative

| Verbs | tú | vos | vosotros / vosotras (*) | usted |
| pensar | piensa | pensá | pensad | piense |
| contar | cuenta | contá | contad | cuente |
| perder | pierde | perdé | perded | pierda |
| moler | muele | molé | moled | muela |
| oler | huele | olé | oled | huela |
| sentir | siente | sentí | sentid | sienta |
| dormir | duerme | dormí | dormid | duerma |
    (*) Only used in Spain. Formal conjugations of the plural imperative end in -d, but in colloquial use the most common conjugation ends in -r instead: pensar, contar, etc.
The verbs sentir and dormir also undergo vowel raising. Additional diphthongizing verbs include acordar(se) (o-ue), divertir(se) (e-ie), doler (o-ue), empezar (-zar e-ie, -ezar), encontrar (o-ue), entender (e-ie), llover (o-ue), morir (o-ue, -morir), mostrar (o-ue), mover (o-ue), poder (o-ue, -poder), probar (o-ue), querer (e-ie, -querer), recordar (o-ue), sentar(se) (e-ie-i), tener (e-ie, -tener, G-Verb), venir (e-ie, -venir, G-Verb), volar (o-ue), and volver (o-ue, -olver).
Many verbs with -e- or -o- in the root do not alternate. Common non-diphthongizing verbs include acercar(se), beber, comer, comprar, conocer, correr, creer, deber, dejar, entrar, esperar, lamentar, llegar, llevar, meter, parecer, poner, prometer, quedar, regresar, responder, suceder, temer, and tomar.
Less frequent verbs of this kind are often a source of mistakes for children learning to speak, and also for some adults:
* rebosar → yo *rebueso, él *rebuesa... instead of yo reboso, él rebosa...

### Vowel raising

Vowel raising appears only in verbs of the third conjugation (-ir verbs), and in this group it affects dormir, morir, podrir (alternative of the more common pudrir) and nearly all verbs which have -e- as their last stem vowel (e.g. sentir, repetir); exceptions include cernir, discernir and concernir (all three diphthongizing, e-ie).

#### Affected forms

The forms that exhibit the change can be described negatively as those in which the stem vowel is not diphthongized and the ending does not contain stressed i or the -ir- sequence. In other words, vowel raising affects the forms whose endings do not contain an i which is not part of a diphthong, taking into account that diphthongizing overrides vowel raising.
In effect, for diphthongizing verbs (e.g. sentir, dormir), the vowel-raising forms are:
* the first-person and second-person plural of the present subjunctive (sintamos, sintáis, durmamos, durmáis);
* the gerund (sintiendo, durmiendo);
* the third-person singular and plural of the preterite (sintió, sintieron, durmió, durmieron);
* all forms of the imperfect subjunctive (sintiera/sintiese..., durmiera/durmiese...) and of the future subjunctive (sintiere..., durmiere...).
For non-diphthongizing verbs (e.g. pedir) it affects these same forms (pidamos, pidáis, pidiendo, pidió, pidieron, pidiera...), plus:
* in the present indicative, all singular forms and the third-person plural (pido, pides, pide, piden);
* the remaining forms of the present subjunctive (pida, pidas, pidan);
* the tú form of the imperative (pide).
The forms which do not undergo either diphthongizing or vowel raising are:
* the first-person and second-person plural of the present indicative (sentimos, sentís), because these forms have stressed i in their endings.
* the infinitive (sentir), past participle (sentido), imperfect indicative (sentía...) and the vos and vosotros/as forms of the imperative (sentí, sentid), for the same reason.
* the future (sentiré...) and conditional (sentiría...), whose endings contain the -ir- sequence.

#### Affected verbs

Verbs which are diphthongizing and vowel-raising include:
* those ending in -entir (sentir, mentir, arrepentirse...) and -ertir (convertir, advertir...).
* those ending in -erir (herir, requerir, preferir, digerir...), except aterir.
* venir and derived verbs (convenir, prevenir...), in the forms that do not undergo other overriding irregularities.
* dormir and morir.
The diphthongizing -er verb poder exceptionally undergoes vowel raising in the gerund (pudiendo), but the first- and second-person plural of the present subjunctive are regular (podamos, podáis).
Non-diphthongizing vowel-raising verbs include:
* those ending in -edir (medir, pedir, despedir...), -etir (competir, repetir) and -egir (corregir, elegir...; note forms with j before a/o such as corrijo, corrija).
* those ending in -eír (reír, sonreír, freír, desleír). Double i that would result is simplified (rieron, not *riieron or *riyeron). The stressed i in contact with a/e/o must take an acute accent (río, ríe, ría) but monosyllabic forms of the preterite do not have it (rio, riais, but rió and riáis were valid before 2010 if pronounced in two syllables).
* those ending in -eñir (teñir, ceñir...). The unstressed i between ñ and a vowel is dropped (tiñendo, tiñó, tiñeron, tiñera...).
* decir and derived verbs (bendecir, predecir...), in the forms that do not undergo other overriding irregularities.
* vestir and derived verbs.
* embestir.
* podrir. The affected forms are equal to those derived from the more usual infinitive pudrir, which is regular except in the past participle podrido.
The vowel-raising verb erguir is usually diphthongizing (with ye- forms such as yergo...). Non-diphthongizing forms are valid but rare (irgo...).

## Diphthongs and hiatus
### Cambio vs. envío

Diphthongs in the infinitive may be preserved throughout the conjugation or broken in the forms which are stressed on the stem, depending on whether the i or u in contact with a/e/o take the stress or not. The stressed vowel is marked bold in the examples: cambiar > cambio, but enviar > envío (requiring an acute accent to indicate the resulting hiatus). The Real Academia Española does not consider either behaviour as irregular, but illustrates each with six "regular" models, one for each possible diphthong in the infinitive: anunciar, averiguar, bailar, causar, peinar and adeudar for diphthong-keeping verbs and enviar, actuar, aislar, aunar, descafeinar and rehusar for diphthong-breaking ones. Remember that the presence of a silent h does not break a diphthong, so a written accent is needed anyway in rehúso.
All verbs ending in -guar are diphthong-keeping, as well as saciar, desairar, restaurar and reinar. Two diphthongs are kept in desahuciar > desahucio (again the -h- makes no difference), which thus follows both the anunciar and causar models.
Diphthong-breaking verbs include ahincar, aislar, aunar, aullar, maullar, aupar, aliar, vaciar, contrariar, evaluar, habituar, reunir. The verbs criar, fiar, guiar, liar and piar are also diphthong-breaking (crío, guíe), but when the stress falls on the endings the resulting forms are generally considered as monosyllables and thus written without accent: crie, fie, guiais, lieis.... In spite of that, the regular accentuation rules can also be used if they are pronounced as bisyllabic: crié, guiáis....
For the verbs licuar and adecuar both options are valid: adecuo or adecúo.
The ui diphthong in cuidar is kept throughout the conjugation despite the fact of the i getting the stress in forms such as cuido (written without stress mark).

### Verbs ending in -uir and -oír

All verbs ending in -uir (e.g. construir, disminuir, distribuir) add a medial -y- before all endings not starting with i: construyo, construyes, construya... Taking into account that these verbs also undergo the change of unstressed intervocalic i to y (see orthographic changes above), they have many forms containing y.
This also applies to the forms of oír and desoír that do not undergo the -ig- change: oyes, oye, oyen…
Some regular forms of fluir, fruir and huir are written without stress mark if considered monosyllabic, but may bear it if pronounced as bisyllabic: vosotros huis or huís (present), yo hui or huí (preterite).
The verb argüir loses the diaeresis before y: arguyo, arguyó… (gü-gu, -güir).

## Other common irregular patterns
### Endings starting with o/a in er/ir verbs

In er and ir verbs, the first person singular of the present indicative and the whole present subjunctive are the only forms whose endings start with o/a instead of e/i. These two different phonetic environments made Latin forms evolve differently in many verbs, leading to irregularities.
Whenever the first person singular of the present indicative has an irregularity other than diphthongizing, but still ends in -o, the whole present subjunctive shares the same irregularity. For example:
* hacer: hago, haga... (-hacer, G-Verb)
* lucir: luzco, luzca... (c-zc, -cir)
* caber: quepo, quepa... (-caber)
* ver: veo, vea...; prever: preveo, prevea... (-ver)
When the first person singular of the present indicative does not end in -o, the present subjunctive is also irregular, but in a different way:
* ser: soy, sea... (-ser, Oy-Verb)
* ir: voy, vaya... (-ir, Oy-Verb)
* haber: he, haya (-haber)
* saber: sé, sepa... (-saber)

#### G-verbs

Before o (in the first person singular of the indicative present tense) and a (that is, in all persons of the present subjunctive), the so-called G-verbs (sometimes "Go-Yo verbs", "Yo-Go" verbs, or simply "Go" verbs) add a medial -g- after l and n (also after s in asir), add -ig- when the root ends in a vowel, or substitute -c- for -g-. This change overrides diphthongization (tener, venir) but combines with vowel-raising (decir). Many of these verbs are also irregular in other ways. For example:
* salir: yo salgo, tú sales... Stem: sal- (-salir)
* valer: yo valgo, tú vales... Stem: val- (-valer)
* poner: yo pongo, tú pones... Stem: pon- (-poner)
* tener: yo tengo, tú tienes... Stem: ten-, tien- (e-ie) (-tener)
* venir: yo vengo, tú vienes... Stem: ven-, vien- (e-ie) (-venir)
* caer: yo caigo, tú caes... Stem: ca-
* traer: yo traigo, tú traes... Stem: tra-
* oír: yo oigo, tú oyes... Stem: o-, oy-
* hacer: yo hago, tú haces... Stem: hac-, haz- (-hacer)
* satisfacer: yo satisfago, tú satisfaces… Stem: satisfac-, satisfaz-
* decir: yo digo, tú dices... Stem: dec-, dic- (e-i) (-decir)
* asir: yo asgo, tú ases... Stem: as-

#### ZC-verbs

This group of verbs—which originated in the Latin inchoative verbs but now includes other verbs as well—substitute -zc- for stem-final -c- before o and a. The group includes nearly all verbs ending in -acer (except hacer and derived verbs), -ecer (except mecer and remecer), -ocer (except cocer and derived verbs), and -ucir. For example:
* nacer: yo nazco, tú naces...
* crecer: yo crezco, tú creces...
* conocer: yo conozco, tú conoces...
* producir: yo produzco, tú produces... (-ducir)
* yacer: yo yazco/yazgo/yago, tú yaces... (-yacer)
Yacer may alternatively be conjugated with -zc- (yazco), -g- (G-Verb) (yago), or a compromise -zg- (yazgo).

### Irregular forms in the future, conditional and imperative

Some -er and -ir verbs (most G-verbs plus haber, saber, poder and querer) also change their stem in the future and conditional tenses. This involves syncope:
* Just dropping the infinitive e: haber → habré..., saber → sabré..., poder → podré..., querer → querré...
* Dropping the infinitive e/i and padding the resulting *-lr-/*-nr- with an epenthetic -d-: tener → tendré..., poner → pondré..., venir → vendré..., valer → valdré..., salir → saldré...
* Dropping the infinitive -ce- or -ec-: hacer → haré..., deshacer → desharé..., decir → diré...
** predecir, contradecir and desdecir may share this irregularity (prediré...) or, more commonly, use the regular forms (predeciré). For bendecir and maldecir only the regular forms are used (bendeciré...).
Many of these verbs also have shortened tú imperative forms (apocope): tener → ten, contener → contén, poner → pon, disponer → dispón, venir → ven, salir → sal, hacer → haz, decir → di. However, all verbs derived from decir are regular in this form: bendice, maldice, desdícete, predice, contradice.

### Anomalous stems in the preterite and derived tenses

Some verbs (including most G-verbs and most verbs ending in -ducir) have a somewhat different stem in the preterite. These stems are very old and often are found in Latin as well. The same irregular stem is also found in the imperfect subjunctive (both in -ra and -se forms) and the future subjunctive. These stems are anomalous also because:
* they are stressed in the first and third persons singular, ending in unstressed -e and -o respectively (while in all other cases the preterite is stressed on the suffix).
* the rest of the endings are the usual for -er/-ir verbs, even for the -ar verbs estar and andar.
* in the verbs with -je preterite (decir, traer, and most verbs ending in -ducir) unstressed i is dropped between the j and a vowel: ellos trajeron, yo trajera... This does not happen with regular or vowel-raising -ger/-jer/-gir/-jir verbs (proteger > protegieron, tejer > tejieron, corregir > corrigieron, crujir > crujieron).
Examples:
* estar: yo estuve, tú/vos estuviste(s), él estuvo..., ellos estuvieron; yo estuviera...
* andar: yo anduve, tú/vos anduviste(s), él anduvo..., ellos anduvieron; yo anduviera...
* tener: yo tuve, tú/vos tuviste(s), él tuvo..., ellos tuvieron; yo tuviera...
* haber: yo hube, tú/vos hubiste(s), él hubo..., ellos hubieron; yo hubiera...
* caber: yo cupe, tú/vos cupiste(s), él cupo..., ellos cupieron; yo cupiera...
* saber: yo supe, tú/vos supiste(s), él supo..., ellos supieron; yo supiera...
* venir: yo vine, tú/vos viniste(s), él vino..., ellos vinieron; yo viniera...
* querer: yo quise, tú/vos quisiste(s), él quiso…, ellos quisieron; yo quisiera…
* poder: yo pude, tú/vos pudiste(s), él pudo..., ellos pudieron; yo pudiera...
* poner: yo puse, tú/vos pusiste(s), él puso..., ellos pusieron; yo pusiera...
* hacer: yo hice, tú/vos hiciste(s), él hizo..., ellos hicieron; yo hiciera...
* satisfacer: yo satisfice, tú/vos satisficiste(s), él satisfizo…, ellos satisficieron; yo satisficiera…
* traer: yo traje, tú/vos trajiste(s), él trajo…, ellos trajeron; yo trajera…
* reducir: yo reduje, tú/vos redujiste(s), él redujo..., ellos redujeron; yo redujera...
* decir: yo dije, tú/vos dijiste(s), él dijo..., ellos dijeron; yo dijera...
The verb ver in modern Spanish has a regular -er verb preterite (yo vi, tú viste, él vio – note the lack of written accent on monosyllables), but in archaic texts the irregular preterite forms yo vide, él vido, etc. are sometimes seen.

### Irregular past participles

A number of verbs have irregular past participles, sometimes called "strong" because the change is in the root, rather than an ending. This includes verbs which are irregular in many other ways, such as poner and decir, but for some other verbs this is their only irregularity (such as abrir and romper), while some very irregular verbs (such as ser and ir) have regular past participles. Examples:
* abrir → abierto, cubrir → cubierto
* morir → muerto, volver → vuelto, solver → suelto
* romper → roto, escribir → escrito
* ver → visto, poner → puesto
* decir → dicho, hacer → hecho, satisfacer → satisfecho
Most of these verbs have derivatives with the same irregularity. For example, alongside volver → vuelto and poner → puesto, there are devolver → devuelto and componer → compuesto; alongside decir → dicho there is predecir → predicho (but note bendecir → bendecido, maldecir → maldecido are regular, though they also have the adjectival forms bendito and maldito). Similarly previsto, rehecho, descubierto, supuesto, etc. Solver is obsolete, but its derivatives absolver and resolver (absuelto, resuelto) are in common use. The participle of describir is descrito in some regions, but descripto in others.
There are three verbs that have both a regular and an irregular past participle. Both forms may be used when conjugating the compound tenses and the passive voice with the auxiliary verbs haber and ser, but the irregular form is generally the only one used as an adjective:
* freír → he freído or he frito, but papas fritas.
* imprimir → he imprimido or he impreso, but papeles impresos.
* proveer → he proveído or he provisto, but una despensa bien provista is far more usual than una despensa bien proveída.
A number of other "strong" past participles, such as pinto, ducho, electo, and a number of others, are obsolete for general use, but are occasionally used in Spain (and to a much lesser extent in Spanish America) among educated, style-conscious writers, or in linguistic archaisms such as proverbs (refranes).

## Others

The verbs ser (to be) and ir (to go) both exhibit irregularities in the present, imperfect and preterite forms (note that these two verbs have the same preterite fui). Together with ver (to see) and prever (to foresee), they are the only four verbs with irregular imperfect indicative. Their tú imperative forms are sé, ve (for both ir and ver, although mirar is more common than ver in commands), and prevé. Their vos imperative forms are sé, andá (the verb andar replaces ir), ve and prevé.
| | Present indicative tense | Present indicative tense | Present indicative tense | Present indicative tense | Imperfect indicative | Imperfect indicative | Imperfect indicative | Imperfect indicative | Preterite | Preterite | Preterite |
| | ser | ir | ver | prever | ser | ir | ver | prever | ser/ir | ver | prever |
| yo | soy | voy | veo | preveo | era | iba | veía | preveía | fui | vi | preví |
| tú | eres | vas | ves | prevés | eras | ibas | veías | preveías | fuiste | viste | previste |
| vos | sos | vas | ves | prevés | eras | ibas | veías | preveías | fuiste | viste | previste |
| él/ella | es | va | ve | prevé | era | iba | veía | preveía | fue | vio | previó |
| nosotros/as | somos | vamos | vemos | prevemos | éramos | íbamos | veíamos | preveíamos | fuimos | vimos | previmos |
| vosotros/as | sois | vais | veis | prevéis | erais | ibais | veíais | preveíais | fuisteis | visteis | previsteis |
| ellos/as | son | van | ven | prevén | eran | iban | veían | preveían | fueron | vieron | previeron |
Note that whenever the preterite is irregular, the imperfect subjunctive (-ra and -se forms) and the dated future subjunctive (-re) share the same irregularity; indeed, these tenses may always be correctly formed by substituting the appropriate endings for the -ron ending of the third person plural preterite: fueron > fuera/fuese...; fuere....
The verbs dar (to give) and estar (to be) both exhibit irregularities in the present indicative and present subjunctive because their stems cannot be stressed (in dar the stem is just d-, in estar it was originally st-). The form dé is so written to distinguish it from the preposition de. Both verbs are also irregular in the preterite and derived tenses: dar follows the pattern of regular -er/-ir verbs, while estar has an anomalous preterite stem and follows the corresponding common pattern:
| | Present indicative | Present indicative | Present subjunctive | Present subjunctive | Preterite | Preterite |
| | dar | estar | dar | estar | dar | estar |
| yo | doy | estoy | dé | esté | di | estuve |
| tú, vos | das | estás | des | estés | diste | estuviste |
| él, ella | da | está | dé | esté | dio | estuvo |
| nosotros/as | damos | estamos | demos | estemos | dimos | estuvimos |
| vosotros/as | dais | estáis | deis | estéis | disteis | estuvisteis |
| ellos/as | dan | están | den | estén | dieron | estuvieron |