---
title: "Infinitive — AP Latin Definition, Uses & Exam Guide"
description: "The infinitive is Latin's unconjugated 'to ___' verb form. It drives indirect statement (accusative + infinitive), one of the most-tested constructions in AP Latin."
canonical: "https://fiveable.me/ap-latin/key-terms/infinitive"
type: "key-term"
subject: "AP Latin"
---

# Infinitive — AP Latin Definition, Uses & Exam Guide

## Definition

In AP Latin, the infinitive is the unconjugated verb form translated 'to ___' (amare, duci, venisse). It completes verbs like possum and volo, serves as a noun, and powers indirect statement, where an accusative subject plus an infinitive reports what someone says, thinks, knows, or perceives.

## What It Is

An infinitive is the [verb](/ap-latin/unit-4 "fv-autolink") form that hasn't been pinned down to a [person](/ap-latin/key-terms/person "fv-autolink") or number. In English it usually looks like "to run" or "to have been seen." In Latin, infinitives come in six main flavors built from tense and voice. Present active (amare, "to love"), present passive (amari, "to be loved"), perfect active (amavisse, "to have loved"), perfect passive (amatum esse, "to have been loved"), future active (amaturum esse, "to be about to love"), and the rare future passive. The second principal part of every verb is its present active infinitive, which is also how you identify a verb's conjugation.

On the AP syllabus ([Vergil](/ap-latin/unit-3 "fv-autolink")'s *Aeneid* and Pliny's *Letters*), the infinitive shows up three big ways. First, the **complementary infinitive** completes verbs like *possum*, *volo*, and *debeo* (Caesar *potest vincere*, "he is able to conquer"). Second, the **infinitive as a noun** can be a subject (*errare humanum est*, "to err is human"). Third, and most important for the exam, the **accusative + infinitive in indirect statement** reports speech and thought after verbs of saying, thinking, knowing, and perceiving. When Caesar writes *dixit hostes venire*, the accusative *hostes* is the subject and the infinitive *venire* is the verb of the reported clause, "he said that the enemy were coming." Caesar's narrative prose runs on this construction, and Vergil adds the **historical infinitive**, an infinitive used in place of a main verb for vivid, rapid-fire action.

## Why It Matters

[AP Latin](/ap-latin "fv-autolink") doesn't test grammar in a vacuum. It tests whether you can read Vergil (Units 1, 3, 5, 8) and Caesar (Units 2, 4, 6, 7) accurately, and you can't translate either author without controlling infinitives. [Indirect statement](/ap-latin/key-terms/indirect-statement "fv-autolink") is everywhere in Caesar because he constantly reports what envoys said, what scouts learned, and what he himself decided. Miss the accusative + infinitive pattern and the whole sentence collapses, because the accusative looks like a direct object when it's actually a subject. The exam's literal-translation FRQs and "identify the form and function" short-answer questions reward exactly this skill. Knowing that the infinitive's tense is *relative* to the main verb (present = same time, perfect = before, future = after) is also what separates a credited translation from a near miss.

## Connections

### [Accusative (Units 1-8)](/ap-latin/key-terms/accusative)

In indirect statement the subject goes into the [accusative](/ap-latin/key-terms/accusative "fv-autolink"), not the nominative. So when you see an accusative noun next to an infinitive after a verb of saying or thinking, read it as "that [accusative] [infinitive]s." This is the single highest-payoff pattern-recognition move in AP Latin.

### [Subjunctive Mood (Units 1-8)](/ap-latin/key-terms/subjunctive-mood)

Latin splits reported language into two lanes. Reported statements take accusative + infinitive, but reported questions and purpose clauses take the subjunctive. If the reporting verb is followed by an interrogative word like *cur* or *quid*, expect a subjunctive instead of an infinitive.

### [Gerund (Units 1-8)](/ap-latin/key-terms/gerund)

Both the infinitive and the gerund are [verbal](/ap-latin/unit-5 "fv-autolink") nouns, but they divide the labor. The infinitive handles the nominative slot (*errare est humanum*), while the gerund supplies the other cases (*ars amandi*, "the art of loving"). Think of the gerund as the infinitive's declinable understudy.

### [Conjugation (Units 1-8)](/ap-latin/key-terms/conjugation)

The present active infinitive is your diagnostic tool for [conjugation](/ap-latin/key-terms/conjugation "fv-autolink"). The vowel before -re (-āre, -ēre, -ere, -īre) tells you whether a verb is first, second, third, or fourth conjugation, which then controls every form you build from it.

## On the AP Exam

Infinitives get tested two main ways. In multiple choice and short-answer questions, you're asked to identify a form's function in a real line of the *Aeneid* or *Roman civil and military history*. A short-answer question on the 2021 exam used the infinitive in exactly this grammatical-identification format. Watch out for the classic trap, though. Exam-style questions love handing you an -nd- form like *vitandum* and asking what it is, precisely because it is NOT an infinitive. It's a gerund or gerundive, and choosing "infinitive" is the designed wrong answer. In the translation FRQs, scoring is segment by segment, so an indirect statement is usually its own scored chunk. You earn it by translating the accusative as the subject ("that the enemy...") and getting the infinitive's relative tense right (perfect infinitive = action before the main verb). Translating *dixit hostes venisse* as "he said the enemy come" instead of "had come" costs the segment.

## Infinitive vs Gerund / gerundive (-nd- forms)

Both are non-finite verb forms often translated with English "-ing" or "to ___," which is why they blur together. The infinitive ends in -re or -isse (or uses esse) and stays indeclinable. A gerund or gerundive ends in -ndus/-nda/-ndum and declines like an adjective. So *vitare* means "to avoid" (infinitive), while *vitandum* is a gerund or gerundive ("avoiding" or "needing to be avoided"). If the form has case endings, it's not an infinitive.

## Key Takeaways

- The infinitive is the unconjugated verb form ("to ___"), and Latin has six of them across present, perfect, and future tenses in active and passive voice.
- Indirect statement uses an accusative subject plus an infinitive after verbs of saying, thinking, knowing, and perceiving, and it is one of the most common constructions in Caesar.
- Infinitive tense is relative to the main verb. Present means same time, perfect means earlier, and future means later than the main verb.
- A complementary infinitive completes verbs like possum, volo, and debeo and is the most basic infinitive use you'll see in both authors.
- Forms ending in -ndum like vitandum are gerunds or gerundives, not infinitives, and the exam uses that confusion as a distractor.
- Vergil uses the historical infinitive in place of a main verb to speed up vivid narrative, a stylistic move worth naming in an analytical essay.

## FAQs

### What is an infinitive in AP Latin?

It's the verb form translated "to ___" (amare, "to love"; venisse, "to have come") that isn't conjugated for person or number. On the AP exam it matters most in indirect statement, where an accusative subject plus an infinitive reports what someone says, thinks, or knows.

### Is vitandum an infinitive?

No. Vitandum is a gerund or gerundive (an -nd- form), not an infinitive. The infinitive of vito is vitare. Exam questions use forms like vitandum specifically to test whether you can tell -nd- verbal nouns and adjectives apart from infinitives.

### How is an infinitive different from a subjunctive in indirect speech?

Reported statements take accusative + infinitive (dixit hostes venire, "he said the enemy were coming"), while reported questions take the subjunctive (rogavit cur venirent, "he asked why they were coming"). If there's a question word after the reporting verb, expect a subjunctive, not an infinitive.

### How do I translate the tense of an infinitive in indirect statement?

Relative to the main verb. A present infinitive means the same time (dixit eos venire, "he said they were coming"), a perfect infinitive means earlier (venisse, "had come"), and a future infinitive means later (venturos esse, "would come"). Getting this wrong is a classic way to lose a translation segment.

### How do I find a verb's conjugation from its infinitive?

Look at the vowel before -re in the present active infinitive. -āre is first conjugation, -ēre is second, -ere (short e) is third, and -īre is fourth. That's why the infinitive is the second principal part of every Latin verb.

## Related Study Guides

- [Multiple-Choice Questions (MCQ)](/ap-latin/ap-latin-exam/ap-latin-mcq/study-guide/ap-latin-mcq)

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