What are Irregular Verbs in Spanish?

Instructor: Janet Long

Janet has taught college Spanish and English courses and has master's degrees in Spanish literature and TESOL.

Did you know that verbs can be regular or irregular? In this lesson you'll learn the difference between regular and irregular verbs and the four categories of irregular verbs in Spanish.

Verbs in Spanish

Verbs are words for the actions that we do, like run or read, and our states of being. In Spanish, every verbs starts with one basic form called the infinitive which ends in either -ar, -er, or -ir. When you make a sentence using the verb, you conjugate, or change, the infinitive to match the subject of the sentence. This means that verbs in Spanish have different spellings depending on who does the action. So, the word for ''I think'', pienso, is different from the word for ''you think'', piensas.

Each group of infinitive endings (-ar, -er, and -ir) has a set of regular conjugations for the different possible subjects, like changing the ending to -o when the subject is ''I'', or yo in Spanish. Each different subject has a regular conjugation for each of the three infinitive endings. However, not all verbs use the regular conjugations. These verbs follow their own sets of rules and are called irregular verbs.

Although irregular verbs in Spanish do no follow the same rules as regular verbs, we can put them into four different categories: verbs that are irregular most of the time, verbs that have an irregular yo (I) form, verbs with stem changes, and verbs with spelling changes. This lesson will focus on how these four groups of irregular verb changes work in the present indicative tense.

Irregular Most of the Time

There are some verbs in Spanish that are irregular most of the time. This means that the changes for the verb rarely or never follow the regular conjugation rules of the infinitive ending on the verb. Many of the most common verbs in Spanish are part of this group. Some common examples include:

Infinitive Translation
Ser to be
Estar to be
Ir to go
Haber to have (used before another verb) / to exist

Sometimes, extra letters or an accent mark are added to the regular verb ending, and other times, the verb uses an ending from a different group of infinitives. These irregular verbs don't follow any predictable rules, so the best thing you can do is memorize and practice them.

Irregular Yo forms

Other verbs are irregular only in the first person singular, or yo form. Verbs can have irregular forms for ''I'' in many different tenses. Some verbs that fall into this category for the present indicative include dar *doy, ver *veo, and saber *sé.

Infinitive Translation yo form
dar to give doy
ver to see veo
saber to know

As you can see, each verb has its own unique irregular change in the yo form. The other forms of the verb follow the regular conjugation rules for the infinitive ending of the verb.

Stem-Changing Verbs

The third type of irregular verbs have letter changes in the stem of the verb. The stem is all of the letters in the verb before the verb ending. In Spanish, it means all of the letters before either -ar, -er, or -ir, depending on the type of verb. For the irregular verbs in this group, one of the letters in the stem of the verb changes when you conjugate the verb. The possible changes include e-ie, o-ue, e-i, and u-ue. You will need to change that letter in the yo, tú, él/ella/usted, and ellos/ellas/ustedes forms. Here is an example from each group of verbs with stem changes: e-ie, o-ue, e-i, and u-ue.

Stem Change Infinitive Translation Conjugation Translation
e-ie cerrar to close cierro I close
o-ue dormir to sleep duermo I sleep
e-i servir to serve sirvo I serve
u-ue jugar to play juego I play

You'll want to remember that these changes happen in all of the conjugations except for the nosotros and vosotros forms of the verbs. For nosotros and vosotros, you will use the the same letters in the stem that are in the infinitive form. Let's look an an example with the verb jugar (to play).

yo juego nosotros jugamos
juegas vosotros jugáis
él/ella/usted juega ellos/ellas/ustedes juegan

Notice that the forms for nosotros and vosotros - jugamos and jugáis both use the letter ''u'' in the stem. This is the same letter that the stem jugar has. So, for these two forms, you'll need to use the same stem spelling as the infinitive.

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