1. What Is a Stem in Verbs?
  2. What Are Stem-Changing Verbs?

Some verbs have changes in their stem when conjugated in the present indicative. Many of these follow the same pattern and can be grouped into three categories. Let's learn how to conjugate them.



Todos los días duermo a las 11:00 p.m.

I go to sleep at 11:00 p.m. every day.

What Is a Stem in Verbs?

Rule 1. For conjugation, two parts of verbs are considered, the stem and the ending. The root or stem of a verb is the part that in a regular verb that does not change during conjugation. What changes is the ending -ar, -er, ir-.

An example of this is the verb cocinar where the stem coci remain the same in all its persons while the -ar ending is removed. Then, the corresponding ending of the present indicative is added to the stem.

Take a look at another example with the verb comer:

Subject pronounsVerb stem (comer)Present indicative endingsVerb in present indicative
yo com o como
com es comes
él, ella, usted com e come
nosotros, nosotras com emos comemos
vosotros, vosotras com éis coméis
ellos, ellas, ustedes com en comen

What Are Stem-Changing Verbs?

Rule 2. As their name suggests, these verbs, in contrast to regular verbs, change their stem in some persons and some tenses. The three most common types of changes that occur in the present indicative are:

o → ue change

Rule 3. This group includes verbs with an o in their stem that will change to ue when conjugated. Let's see an example with the verb dormir:

Subject pronounsVerb dormir
yo duermo
él, ella, usted duerme
nosotros, nosotras dormimos*
vosotros, vosotras dormís*
ellos, ellas, ustedes duermen

As you will note in the table, this change affects all persons except nosotros, nosotras, and vosotros, vosotras which act as regulars.



Mis hermanos deportistas siempre duermen temprano.

My sporty brothers always sleeps early.

Nosotras siempre dormimos tarde porque tenemos mucha tarea.

We always sleep late because we have a lot of homework.

Other verbs that have this change are:

  • almorzar,
  • costar,
  • devolver,
  • encontrar,
  • llover,
  • morir,
  • poder,
  • soñar (con).

The Verb Jugar

Rule 4. The verb jugar is conjugated in a similar way to verbs with a change of stem o → ue. However, since it does not have an o sound in the stem, the letter u is the one that will make the change to ue.



Juego videojuegos todos los días después de trabajar, me ayuda a relajarme.

I play video games every day after work, it helps me relax.

e ➝ ie change

Rule 5. Another category is verbs that have i in their stem that changes to ie. Let's see an example with the verb querer:

Subject pronounsVerb querer
yo quiero
él, ella, usted quiere
nosotros, nosotras queremos*
vosotros, vosotras queréis*
ellos, ellas, ustedes quieren

Similar to the verbs with the o → ue change, nosotros, nosotras, vosotros and vosotras don't change their stem.

Other verbs in this category are:

  • cerrar,
  • mentir,
  • encender,
  • nevar
    empezar (a),
  • pensar,
  • encender,
  • perder,
  • entender,
  • preferir,
  • comenzar.



Cierra la puerta cuando salgas por favor.

Please close the door on your way out.

e ➝ i change

Rule 6. The last category covers some -ir verbs in which the stem e changes to i. Like in the other categories, these verbs also change in all forms except nosotros/as and vosotros/as. Let's see an example with the verb repetir:

Subject pronounVerb repetir
yo repito
él, ella, usted repite
nosotros, nosotras repetimos
vosotros, vosotras repetís
ellos, ellas, ustedes repiten

Other verbs that present these changes are

  • reír*,
  • competir,
  • pedir.

*The verb reír keeps its accent mark in the conjugation.



¿Ríes mucho con los shows te comedia?

Do you laugh a lot at comedy shows?

Familiarizing yourself with these stem changes will not only help you with the conjugation of the present indicative, but also with the verb conjugation in other tenses. So let's practice!



Yo _________ (almorzar) todos los días al mediodía.


correct answers.