Latin Verbs - Infinitives

When you look up a Latin verb in a Latin-English lexicon or dictionary, you will see four entries for most verbs. The first entry is the present, active, singular, first person form of the verb. The next entry, usually abbreviated to "-are," "-ere" or "-ire," is the infinitive. More specifially, it's the present active infinitive, which is translated into English as "to" plus whatever the verb means.

Example: Laudo, -are, -avi, -atus. Praise

Laudo is a first conjugation verb and therefore has an infinitive ending in "-are." The entire present active infinitive of laudo is laudare, which we translate into English as "to praise." (Laudo literally means "I praise.")
Laudari is the present passive infinitive of laudo and means "to be praised."

Most verbs have six infinitives:

1. Present Active
2. Present Passive
3. Perfect Active
4. Perfect Passive
5. Future Active
6. Future Passive (rare)

The perfect active infinitive is formed from the perfect stem. In our example of a first conjugation verb, laudo, the perfect stem is found on the third principal part, laudavi, which is listed in the dictionary simply as "-avi." Remove the personal ending ("i") and add "isse" -- laudavisse -- to make the perfect active infinitive. The perfect passive infinitive is formed from the fourth principal part, in our example, laudatus, plus "esse." The perfect passive infinitive is laudatus esse. The fourth principal part also informs the future infinitives. The future active infinitive is laudaturus esse and future passive infinitive is laudatum iri.

First Conjugation

1. (Present Active) amare (love)
2. (Pres. Passive) amari
3. (Perf. Act.) amavisse
4. (Perf. Pass.) amatus esse
5. (Fut. Act.) amaturus esse
6. (Fut. Pass.) amatum iri

Second Conjugation

1. monere (warn)
2. moneri
3. monuisse
4. monitus esse
5. moniturus esse
6. monitum iri

Third Conjugation

1. regere (rule)
2. regi
3. rexisse
4. rectus esse
5. recturus esse
6. rectum iri

Fourth Conjugation

1. audire (hear)
2. audiri
3. audivisse
4. auditus esse
5. auditurus esse
6. auditum iri