Warning
this is my quick reference/refresher sheet. if you're not already familiar with it, I recommend the LatinTutorial video on infinitives or otherwise having it taught and explained.
six forms of the infinitive:
present active/passive
perfect active/passive
future active/passive
mixed conjugation follow 3rd conjugation forms for all infinitives.
| present | perfect | future | |
|---|---|---|---|
| active | amare | amavisse | amaturus (-a -um) [esse] |
| passive | amari | amatus (-a -um) esse | too rare to care |
present
active & passive
- 1st conj: stem + long a + [-re (active) -rī (passive)]
- amāre, amārī
- 2nd conj: stem + long e + [-re (active) -rī (passive)]
- monēre, monērī
- 3rd/mixed conj: stem + [[short e + re (active)], -ī (passive)]
- ducere, ducī
- the present passive infinitive often looks like a perfect 1st person singular, for some verbs they are the same
- defendo, defendere, defendi, defensum
- present passive infinitive = defendi
- 4th conj: stem + long i + [-re (active) -rī (passive)]
- audīre, audīrī
perfect
active
perfect stem + isse, e.g. amavisse
passive
the PPP (which is declined in agreement with the thing the verb is acting on) + esse, amatus esse, amata esse, amatum esse
future
active
the future active participle (which is declined in agreement with the thing the verb is acting on) + optional esse.
amaturus esse, amatura esse, amaturum esse
passive
accusative supine + īrī
- accusative supine ~= 4th principle part
- the supine bit does not decline in agreement with anything
- future passive infinitive is very rare, except in Cicero
- īrī is the present passive infinitive of eō, īre, īvī, itum