Stem-Changing Verbs (E→IE, O→UE)

Stem-changing verbs, also called "boot verbs" (verbos con cambio de raiz), are among the most commonly used verbs in Spanish. They follow the regular -AR, -ER, or -IR endings, but the vowel in the stem changes in certain forms. Understanding these patterns is essential for natural-sounding Spanish.

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Why "Boot Verbs"?

The stem change occurs in all forms except nosotros and vosotros. If you draw a line around the forms that change, the shape looks like a boot:

    yo (change)          nosotros (NO change)
    tu (change)          vosotros (NO change)
    el/ella (change)     ellos/ellas (change)

The forms inside the "boot" have the stem change. The forms outside the boot (nosotros and vosotros) keep the original stem.

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Type 1: E → IE

In these verbs, the e in the stem changes to ie in the boot forms.

querer (to want / to love)

Subject	Conjugation	Stem Change?
yo	quiero	Yes
tu	quieres	Yes
el/ella/usted	quiere	Yes
nosotros/as	queremos	No
vosotros/as	quereis	No
ellos/ellas/ustedes	quieren	Yes

pensar (to think)

Subject	Conjugation	Stem Change?
yo	pienso	Yes
tu	piensas	Yes
el/ella/usted	piensa	Yes
nosotros/as	pensamos	No
vosotros/as	pensais	No
ellos/ellas/ustedes	piensan	Yes

More E → IE verbs

Infinitive	English	yo form
entender	to understand	entiendo
preferir	to prefer	prefiero
cerrar	to close	cierro
empezar	to begin	empiezo
perder	to lose	pierdo
sentir	to feel	siento
mentir	to lie	miento
despertar	to wake up	despierto

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Type 2: O → UE

In these verbs, the o in the stem changes to ue in the boot forms.

poder (to be able to / can)

Subject	Conjugation	Stem Change?
yo	puedo	Yes
tu	puedes	Yes
el/ella/usted	puede	Yes
nosotros/as	podemos	No
vosotros/as	podeis	No
ellos/ellas/ustedes	pueden	Yes

dormir (to sleep)

Subject	Conjugation	Stem Change?
yo	duermo	Yes
tu	duermes	Yes
el/ella/usted	duerme	Yes
nosotros/as	dormimos	No
vosotros/as	dormis	No
ellos/ellas/ustedes	duermen	Yes

More O → UE verbs