Boot Stems

Boot stems are the most common irregular stems. They apply in the present indicative and subjunctive forms when the stress falls on the stem (all pronouns except nosotros and vosotros). They always involve a change to the stem vowel -- the last vowel in the stem, and follow a handful of common patterns (e.g. e -> ei).

Boot stems are are weak stems that may be overridden by strong Preterite, Preterite-J, or Subjunctive stems.

There are a 6 common Boot-stem vowel change patterns, where the stem vowel (the last vowel in the stem) changes in Boot positions (e.g. o → ue). There is one model verb for each Boot-stem change pattern, as shown in the table below.

Model Verb	Irregular Stem(s)	Vowel-Change Pattern	No. of Verbs
mover	muev·es	o → ue	12
contar	cuent·es	o → ue	34
acertar	aciert·es	e → ie	36
entender	entiend·es	e → ie	10
dormir	duerm·es	o → ue	1
adquirir	adquier·es	i → ie	0
sentir	sient·es + sint·iendo	e → ie	24
pedir	pid·es + pid·iendo	e → i	19

Boot stem reference table

Pronoun	Tense	Ending
yo	Present	o
tú	Present	as/es
él	Present	a/e
ellos	Present	an/en
yo	Subjunctive	e/a
tú	Subjunctive	es/as
él	Subjunctive	e/a
ellos	Subjunctive	en/an
tú	Imperative	a/e
él	Imperative	e/a
ellos	Imperative	en/an