An intro to Spanish stem-changing verbs

Have you ever wondered why some verbs in Spanish are spelled one way in the infinitive but then a vowel is added or changed once it is conjugated? For example, the verb querer (to love, to want) when conjugated in the yo form changes to quiero. Why is that? Sometimes we know grammar rules and vocabulary but don’t really understand why some changes occur.

In this article, you will learn what stem-changing verbs are, you will have a better understanding of the reason behind some of those stem changes, you will see the conjugations of some common stem-changing verbs in the present, preterite, and present progressive tenses, and finally, you will have a chance to practice what you learned. Sounds good?

Stem-changing verbs

Stem-changing verbs are, as the name indicates, verbs with a change in their stem. A stem or root is the part of the verb that appears in all the forms and carries the general or fundamental meaning. To figure out what the stem of a verb is, just remove the -ar, -er, or -ir ending from the infinitive form. For example, the stem of the verb querer would be quer- and then we would add the appropriate endings according to the conjugation. However, since it is a stem-changing verb, the stem changes from quer- to quier- in the present tense: Quiero (I want)

Before we get into the conjugation of stem-changing verbs, let’s briefly talk about WHY this happens. This stem change is due to diphthongization which is when a vowel turns into a diphthong (when two vowels occur in one syllable). This process happened over time as Latin evolved into Spanish. Not only verbs (dormo => duermo) underwent a change but other words as well: porta => puerta, mortem => muerte, dentem => diente.

Keep in mind that many other changes happened with the evolution from Latin to Spanish. Not only did some vowels change, but consonants did as well. For example the C to G in words like amicum to amigo (friend), cattus to gato (cat); or Q to G in aquam to agua (water). Interesting, isn’t it? I am sure you have heard and use Latin words in English. Can you think of any?

Stem-changing verbs in the present tense

You should now have a better idea of what stem-changing verbs are and why there is a change. So how many changes are there? In the present tense there are three types of stem changes:

• e:ie: querer, pensar, preferir, perder
• e:i: repetir, pedir, medir
• o:ue: dormir, morir, poder, mover

There are two more, but they only happen in one and two verbs respectively.

u:ue: jugar is the only verb that has a u:ue stem change.

i:ie: There are only two verbs that have an i:ie change: adquirir (to acquire) and inquirir (to inquire). 

What happens when you have two vowels in the stem? Do both change? Only the second vowel changes. Take a look at the following verb preferir:

The stem of preferir is prefer- 

It is an e:ie stem-changing verb

Since the stem has two Es, you will change the second one: prefiero (I prefer).

Same thing happens with repetir (e:i) or empezar (e:ie), the second e would be the one that changes.

e:ie

Let’s conjugate preferir in the present tense:

yo prefiero

tú prefieres

él / ella / usted prefiere

nosotros / nosotras preferimos

(vosotros / vosotras preferís)

ellos / ellas / ustedes prefieren

Did you notice that the first and second person plural do not have a stem change?

More e:ie verbs

• Acertar - to guess,
• Encender - to light
• Advertir - to advise, warn
• Entender - to understand
• Cerrar - to close, shut
• Comenzar - to begin
• Hervir - to boil
• Confesar - to confess
• Mentir - to lie
• Consentir - to consent
• Negar - to deny
• Convertir - to convert
• Pensar (en) - to think about
• Defender - to defend
• Empezar - to begin

¡Ojo! The verb tener (to have) is one of the most irregular verbs in Spanish. Not only is it a stem-changing verb, but it is also irregular in the yo form: tengo. The verb venir (to come) shares the same pattern as tener: it is also irregular in the yo form and has a stem change. Let’s compare the conjugations:

Tener

yo tengo

tú tienes

él / ella / usted tiene

nosotros / nosotras tenemos

(vosotros / vosotras tenéis)

ellos / ellas / ustedes tienen

Venir

yo vengo

tú vienes

él / ella / usted viene

nosotros / nosotras venimos

(vosotros / vosotras venís)

ellos / ellas / ustedes vienen

e:i

Let’s take a look at the conjugation of an e:i stem-changing verb:

yo repito

tú repites

él / ella / usted repite

nosotros / nosotras repetimos

(vosotros / vosotras repetís)

ellos / ellas / ustedes repiten

More e:i verbs

• Competir - to compete
• Concebir - to conceive
• Despedir - to fire
• Impedir - to impede
• Reñir - to scold, quarrel
• Servir - to serve
• Teñir - to color, dye
• Vestir - to dress

o:ue

What about the conjugation of an o:ue verb? Let’s conjugate the verb recordar (to remember) in the present tense:

yo recuerdo

tú recuerdas

él / ella / usted recuerda

nosotros / nosotras recordamos

(vosotros / vosotras recordáis)

ellos / ellas / ustedes recuerdan

More o:ue verbs

• Almorzar - to eat lunch
• Morir - to die
• Aprobar - to approve
• Mostrar - to show
• Colgar - to hang
• Mover - to move (an object)
• Contar - to count, to tell
• Probar - to prove, test, sample, taste
• Costar - to cost
• Devolver - to return (an object)
• Resolver - to solve
• Volver - to return (from someplace)
• Rogar - to beg, pray
• Dormir - to sleep
• Sonar - to sound, ring
• Encontrar - to find
• Soñar (con) - to dream (about)
• Envolver - to wrap
• Morder - to bite
• Volar - to fly

Fun fact! Stem-changing verbs are also called “boot verbs” by Spanish learners. Do you know why? When you conjugate a stem-changing verb in two columns (1st, 2nd, and 3rd person singular in one column and 1st, 2nd, and 3rd person plural in another column) if you draw a line around the forms that change (in the present tense), the resulting shape looks like a boot (if you draw well, of course). Try it! Can you see a boot? 

Stem-changing verbs in the preterite (pretérito perfecto)

There are also changes in the preterite tense; however, it’s a bit more simple: 

• Only –ir verbs are stem-changing
• The change only happens in the third person singular and plural
• The changes are only e:i and o:u

For example:

e:i change: Mentir (to lie)

yo mentí

tú mentiste

él / ella / usted mintió

nosotros / nosotras mentimos

(vosotros / vosotras mentisteis)

ellos / ellas / ustedes mintieron

o:u change: Dormir (to sleep)

yo dormí

tú dormiste

él / ella / usted durmió

nosotros / nosotras dormimos

(vosotros / vosotras dormisteis)

ellos / ellas / ustedes durmieron

Stem-changing verbs in the present progressive tense

Remember that the present progressive is formed with the present of the verb estar and the gerund form of a verb: Yo estoy hablando, Ella está comiendo.

In the present progressive, only -ir verbs have a stem change, and it’s an e:i or o:u change just like in the preterite tense.

For example:

e:i change

servir: El camarero está sirviendo la comida.

Other e:i verbs in the present progressive: pedir: pidiendo; decir: diciendo.

o:u change

dormir: Los niños están durmiendo desde las 8.

Other o:u verbs in the present progressive: morir: muriendo; poder: pudiendo.

Conclusion

That wasn’t that bad, was it? Hopefully, you have a better understanding of what stem-changing verbs are, why they change, and the types of changes in the present (e:ie, e:i, o:ue, and some special verbs like jugar, adquirir, and inquirir). You also learned that there are changes in the preterite tense (only e:i and o:u and only in the 3rd person forms, singular and plural); and finally, we covered the changes that occur in the gerund form of the present progressive tense (pidiendo, pudiendo).

I think you’re ready for some practice!

Quiz

Conjugate the following stem-changing verbs in the present tense

If you don’t know a term, don’t forget to look it up in an online dictionary such as https://www.linguee.com/english-spanish.

1. Nosotros _____ (almorzar) en casa a las tres de la tarde.
2. Cristina no ______ (poder) ir al cine esta noche.
3. Raúl _______ (tener) mucho trabajo este fin de semana.
4. ¿Ellos ________ (entender) la clase de matemáticas?
5. Mis hermanos ________ (jugar) al fútbol en el parque los fines de semana.

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Answer key:

1. almorzamos
2. puede
3. empieza
4. entienden
5. juegan

Conjugate the following stem-changing verbs in the preterite tense

1. La profesora __________ (repetir) los verbos para los estudiantes.
2. Alicia se __________ (divertir) con sus hermanos en su cumpleaños.
3. ¿Tus amigas nunca te _________ (mentir)?
4. Evaristo _________ (perder) la cartera el sábado pasado.
5. Matilde _________ (preferir) tomar té.

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Answer key:

1. repitió
2. divirtió
3. mintieron
4. perdió
5. prefirió

Conjugate the following stem-changing verbs in the present progressive tense

1. El gato _____________________ (pedir) la comida.
2. Los niños ____________________(repetir) lo que dice la profesora.
3. Ana ____________________(seguir) a su mamá por la casa.
4. Papá ___________________(servir) la cena.
5. Creo que Juan me ______________ (mentir).

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Answer key:

1. está pidiendo
2. están repitiendo
3. está siguiendo
4. está sirviendo
5. está mintiendo