The Latin Infinitive - Other Verb Types

Along with regular verbs, deponent, semi-deponent and irregular verbs can all form infinitives (though none of these verbs can form all of the infinitives).

Deponent and Semi-deponent Verbs

The Latin infinitive is formed in three tenses: present, perfect and future. All three tenses can be formed with deponent and semi-deponent verbs. The Latin verbs called deponent are formed using passive voice endings but are translated using the active voice. Semi-deponent verbs are those that are translated entirely in the active voice but divided in their formation: the present system uses active voice forms, but the perfect system uses passive voice forms.

Present infinitive:
- It is the 2nd principal part of the verb, whether deponent or semi-deponent.
- The deponent forms will look passive (end in -ri or -i).
- The semi-deponent forms will look active (end in -re).
- Translate in the active voice.
Perfect infinitive:
- Formed using the perfect passive formation rules (perfect participle + esse)
- Translate in the active voice.
Future infinitive:
- Formed using the same rules as the future active infinitive for regular verbs (future participle + esse)
- Translate in the active voice.

Infinitive Examples - Deponent and Semi-Deponent Verbs

Let's explore these infinitives using the following verbs:

1st Conjugation Deponent:
- arbitror, arbitrari, arbitratus sum - to think
3rd Conjugation Deponent:
- sequor, sequi, secutus sum - to follow
2nd Conjugation Semi-Deponent:
- audeo, audere, ausus sum - to dare

**Deponent and Semi-Deponent Infinitive Examples**
Present	Perfect	Future
arbitrari - to think sequi - to follow audere - to dare	arbitratus, a, um esse - to have thought secutus, a, um esse - to have followed ausus, a, um esse - to have dared	arbitraturus, a, um esse - to be about to think secuturus, a, um esse - to be about to follow ausurus, a, um esse - to be about to dare

Nota bene

Future Active Infinitive for deponent verbs: this is the same method we used when forming the future active infinitive for regular verbs, making the future infinitive an active looking deponent form. This is very rare as deponents are defined as forms that use passive-looking forms, though they are translated in the active voice.

Irregular Verbs

Refer to the following chart for the infinitive forms for the irregular verbs. The following formation rules apply for the compound versions of these verbs as well.

sum, esse, fui, futurus - to be
eo, ire, ii (ivi), itus - to go
volo, velle, volui - to want
fero, ferre, tuli, latus - to bring, bear
fio, fieri, factus sum - to be made, to become

Irregular Verb Infinitives
Tense Voice	esse	ire	velle	ferre	fieri**
Present Active	esse to be	ire to go	velle to want	ferre to bring	fieri to become
Perfect Active	fuisse to have been	iisse (ivisse) to have gone	voluisse to have wanted	tulisse to have brought	factus, a, um esse to have become
Future Active	futurus, a, um esse to be about to be	iturus, a, um esse to be about to go	N/A	laturus, a, um esse to be about to bring	factum iri to be about to become
Present Passive	N/A	iri*	N/A	ferri to be brought	fieri to be made
Perfect Passive	N/A	N/A	N/A	latus, a, um esse to have been brought	factus, a, um esse to have been made
Future Passive	N/A	N/A	N/A	latum iri to be about to be brought	factum iri to be about to be made

Nota Bene

*The present passive infinitive form of the verb ire (iri) is never used by itself in translation. Rather, it is used as part of the formation for the future passive infinitive, as the form following the supine:
- amatum iri - to be about to be loved\
**For the irregular verb fieri, note that the infinitive forms were written for both active and passive, but were the same forms. The verb fieri has both active and passive translations for each form.

Additional Notes about Irregular Verb Infinitives

The future participle for esse is often abbreviated:
- fore
- This will be the abbreviation, regardless of the ending on the participle:
  - futura esse = fore
  - futuros esse = fore
The compound forms of velle will form the following infinitives:
- nolo, nolle, nolui
  - Present Active: nolle - to not want
  - Perfect Active: noluisse - to have not wanted
- malo, malle, malui
  - Present Active: malle - to prefer
  - Perfect Active: maluisse - to have preferred

Practice Activity