The Infinitivo is one of the three formas nominais (nominal forms) verbs can have. These nominal forms do not express the verb tense, mode, and person by themselves, as they are dependent on the context in which they appear.
The infinitivo expresses the idea of an action and it could be thought of as the base form of the verb.
There are two types of infinitivo: Impessoal (Impersonal) and Pessoal (Personal). We’ll dive into each type below and explain the differences.
The Infinitivo Impessoal (impersonal infinitive) is invariable, meaning it appears without any conjugation as it doesn’t have a subject.
É obrigatório lavar as mãos.Washing hands is mandatory.
The example above is not referring to anyone specific, just to the general idea of “washing”.
However, the infinitive can also appear as the subject of a sentence itself.
Errar é humano.To err is human.
Amar é viver.To love is to live.
Again here, the verbs refer to the general idea of the action, rather than to a specific person doing the action.
The Infinitivo Pessoal (personal infinitive) differs because there is a known subject. It is formed by adding the terminations -es (tu) , -mos (nós), -des (vós) and -em (eles, elas, vocês) to the Infinitivo Impessoal. (Because the 2nd person plural vós is rarely used nowadays, we’ll focus our attention on the other three.)
The following table shows how the Infinitivo Pessoal is conjugated with three different verbs.