Fourth Conjugation Paradigm
The fourth conjugation is the long-ī family. Its model verb audiō, audīre, audīvī, audītum ("hear") wears that ī on its sleeve: audīs, audīt, audīmus, audītis — a long ī runs through the whole present system.
Set capit (3rd-iō, short i) next to audīt (long ī) and you've found the conjugation in one vowel.
The family is small but high-traffic: audiō, veniō, sciō, sentiō, dormiō, mūniō, custōdiō, aperiō, reperiō run through Caesar and Vergil on every page. Two traps catch students.
The 3rd-plural audiunt ends in -iunt, not -īunt — the ī shortens before -unt. And the future borrows 3rd-conjugation flavor: audiam, audiēs, audiet mirror regam, regēs, reget, not amābō, amābis.
The long-ī family — small but high-frequency, with a 3rd-conjugation future and a tell-tale -iunt in the 3rd plural.
The long ī shortens before -unt (audiunt) and before any vowel-initial subjunctive ending (audiam, audiās). Distinguish from 3rd-iō by vowel length: audīt (long) vs. capit (short).
| Case | Singular | Plural |
|---|---|---|
| 1st pres. ind. | aud-iō | aud-īmus |
| 2nd pres. ind. | aud-īs | aud-ītis |
| 3rd pres. ind. | aud-it | aud-iunt |
| 1st impf. ind. | aud-iēbam | aud-iēbāmus |
| 1st fut. ind. | aud-iam | aud-iēmus |
| 2nd fut. ind. | aud-iēs | aud-iētis |
| 1st pres. subj. | aud-iam | aud-iāmus |
| 1st perf. ind. | aud-īvī | aud-īvimus |
| perf. pass. ppl. | aud-ītus, | aud-ītī, |
| pres. infin. | aud-īre | — |
| pres. imperative | aud-ī | aud-īte |
| pres. ppl. | aud-iēns, | — |
See It In Action
— Verg. Aen. i. 2
Veniō is the second-most-common 4th-conjugation verb after audiō. Notice the perfect vēnit keeps the long stem-vowel; the 4th conjugation telegraphs its identity through vowel length even into the perfect.
— B. G. i. 18
Sentiēbat shows the imperfect formula at work: stem senti- + tense-sign -ēbā- + personal ending -t. The same shape powers audiēbat, veniēbat, mūniēbat — one rule, the whole conjugation.
— B. G. i. 20
Caesar lands the contrast in one breath: scīre (4th, long ī) sits next to capere (3rd-iō, short e). Same -iō family, different conjugations — the infinitive vowel is the giveaway.
— Sall. Cat. 45
Sallust's brisk aperit shows the present-stem vowel pattern at full speed. Compare with the perfect aperuī (Sallust's perfect of choice for aperiō) — the 4th conjugation's perfect can be -īvī (audīvī) or -uī (aperuī) depending on the verb.
Both look like -iō verbs in the first person singular. The deciding test is the vowel length in the 3rd singular and the infinitive.
stem-vowel long ī — audīt ("he hears"), infinitive audīre
audīt, audīre, audiunt
long ī in audīt and audīre; -iunt in 3rd plural
stem-vowel short e/i — capit ("he takes"), infinitive capere
capit, capere, capiunt
short i in capit, short e in capere; same -iunt in 3rd plural
Tip: Look at the infinitive AND the 3rd singular. -īre + long ī in the singular = 4th. -ere + short i in the singular = 3rd-iō. The 3rd-plural -iunt is shared and never tells you which family you're in.
In the line Italiam… venit (Verg. Aen. i. 2), what conjugation does venit belong to, and what is the 3rd-plural form of the same tense?
Study Tips
- •Memorize audiō, audīre, audīvī, audītum as your template — every other 4th-conjugation verb conjugates the same way.
- •Mark the ī long with a macron when you write paradigms out. The vowel length is the WHOLE point of the conjugation; losing the macron loses the lesson.
- •Drill the future side-by-side with 3rd conjugation: audiam ~ regam, audiēs ~ regēs. Then drill the present side-by-side with 3rd-iō: audīt ~ capit, audiunt ~ capiunt.
- •When you see -iunt in a Caesar narrative, read it twice — veniunt (4th, "they come") and capiunt (3rd-iō, "they take") share that ending, but the rest of the paradigm tells you which conjugation it belongs to.