What is the meaning of -ir?

forms infinitives

forms the infinitives of many verbs

Used to denote the past infinitive of a verb.

A verb ending for infinitives.

used to form infinitives of second conjugation verbs

used to create agent nouns from class 1 weak verbs

forms the infinitive of the third-conjugation verbs

a verb ending for infinitives

verb suffix for the impersonal present indicative/future

Source: wiktionary.org