infinitive

An ‘infinitive’ is the basic form of a verb that usually goes after ‘to’.
Usually, when we say ‘infinitive’ we mean the most common: present infinitive after ‘TO’ (the basic/base form of verbs that we learn first or find in dictionaries).
The infinitive can also take a perfect, continuous, and passive form or a combination of those.

It can function as a noun, adjective, or adverb