Spanish infinitive

The infinitive (el infinitivo) is the basic form of a verb that you find when you look it up in a dictionary. It is a non-finite (or "in-finite", hence infinitive) verb form (like participles and gerunds), which means that it has no expressed or implied subject and shows no tense.

In English, do and write are infinitives, although we usually place the word to in front of them (i.e. to do, to write) to make it clear that we are talking about the infinitive. Additionally, many constructions in English use the infinitive preceded by to. For example:

  • "He wants to go there" uses the infinitive with to: the full infinitive (or to-infinitive).
  • "He must go there" uses the infinitive without to: the bare infinitive.

In Spanish, infinitives end in -ar -er or -ir, which gives an indication of the verb family (or conjugation) that they belong to. For example: hablar (to talk), beber (to drink), vivir (to live). Here are example sentences using these infinitives:

Nosotros vamos a hablar con ella.
We are going to talk to her.

No debéis beber tanto vino.
You must not drink so much wine.

Me gustaría vivir contigo.
I would like to live with you.

The Spanish infinitive is very often used after modal verbs (e.g. deber, poder) and after many other verbs, nouns or adjectives, sometimes linked by a preposition (e.g. a, de) and sometimes not (you just have to learn this!). Here is a short text that illustrates this varied use:

Yo quiero encontrar un trabajo. He empezado a buscar un trabajo. Sin embargo, todavía no he sido capaz de encontrar un trabajo. Necesito ganar algún dinero y estaré muy contento de trabajar. ¡Debo encontrar un trabajo!

I want to find a job. I have started to look for a job. However, I have not yet been able to find a job. I need to earn some money and I would be happy to work. I must find a job!

All prepositions, when followed by a verb in Spanish, are followed by the infinitive. In English, prepositions except to take the -ing form of the verb. For example:

Debes comer antes de estudiar.  
You must eat before studying.

No puedes salir sin comer.  
You can't go out without eating.

En vez de ir a pie, podríamos coger el autobús.  
Instead of going on foot, we could take the bus.

  1. It is used when the verb is used as a noun, usually the same as the English gerund (-ing form used as a noun):

    Encontrar un trabajo no es fácil.
    Finding a job is not easy.

  2. It can also be used to summarise an action, without indicating time or tense:

    ¿Pagar 100 euros por comprar un billete? No me digas!
     Pay 100 Euros to buy one ticket? No way!

    Salir sin abrigo en invierno: ¡es una locura!
    Go out without a coat in winter: that's crazy!

  3. It is also used for commands in contexts such as instructions and notices:

    Abrir aquí.
    Tear here.

    No correr por los pasillos.  
    Do not run in the corridors. 

Clever stuff happening!