---
title: "Passive Periphrastic — AP Latin Definition & Exam Guide"
description: "The passive periphrastic pairs a gerundive with a form of sum to express necessity (\"must be done\"). Learn how AP Latin tests it with words like vitandum."
canonical: "https://fiveable.me/ap-latin/key-terms/passive-periphrastic"
type: "key-term"
subject: "AP Latin"
---

# Passive Periphrastic — AP Latin Definition & Exam Guide

## Definition

The passive periphrastic is a Latin construction that combines a gerundive (the -ndus, -nda, -ndum verbal adjective) with a form of sum to express obligation or necessity, translated "must be" or "has to be," with the person responsible expressed by a dative of agent.

## What It Is

The passive periphrastic is Latin's way of saying something *must* happen. It has two parts: a **[gerundive](/ap-latin/key-terms/gerundive "fv-autolink")** (a [verbal](/ap-latin/unit-5 "fv-autolink") adjective ending in -ndus, -nda, -ndum) plus a form of **sum**. So *hoc faciendum est* means "this must be done," and the famous *Carthago delenda est* means "Carthage must be destroyed." The gerundive behaves like any adjective, agreeing with its subject in gender, number, and case, which is why you'll see *vitandum* (neuter) with a neuter subject but *vitanda* with a feminine one.

Here's the twist that makes it a test favorite. When Latin wants to say *who* must do the action, it doesn't use *ab* + ablative like a normal passive. It uses the **dative of agent**. *Nobis hoc faciendum est* literally means "this is to-be-done by us," or more naturally, "we must do this." That double translation (literal vs. smooth) is exactly the move [AP Latin](/ap-latin "fv-autolink") translation questions reward.

## Why It Matters

The passive periphrastic shows up across the entire AP Latin syllabus because both [Caesar](/ap-latin/key-terms/caesar "fv-autolink") and [Vergil](/ap-latin/unit-3 "fv-autolink") use it constantly. Caesar in particular leans on it when describing military necessity, since everything in the *Gallic War* seems to be something that *must be done* right now. The construction sits at the intersection of two skills the course assesses heavily: grammatical analysis (identifying what a form like *vitandum* is actually doing in a sentence) and literal translation (rendering necessity as "must be" rather than paraphrasing it away). If you can't spot a periphrastic, you'll mistranslate the whole clause, and translation scoring on the exam is segment-by-segment, so one missed construction costs real points.

## Connections

### [Adjective Agreement (Units 1-8)](/ap-latin/key-terms/adjective-agreement)

The gerundive is a verbal [adjective](/ap-latin/key-terms/adjective "fv-autolink"), so the same agreement rules you learned for ordinary adjectives apply. It must match its subject in gender, number, and case. If you see vitanda with a feminine plural subject, agreement is the clue that tells you they go together.

### Ablative Case and Agent (Units 1-8)

Normal passive [verbs](/ap-latin/unit-4 "fv-autolink") express the agent with ab plus the ablative. The passive periphrastic breaks that rule and uses the dative of agent instead. This is one of the most-tested case distinctions in the course because it looks wrong until you know the rule.

### [Ablative Absolute (Units 1-8)](/ap-latin/key-terms/ablative-absolute)

Like the ablative absolute, the passive periphrastic is a compact verbal construction that Latin uses where English would need a whole clause. Both are favorite targets for grammatical-function questions, and both demand a [literal translation](/ap-latin/unit-2 "fv-autolink") first before you smooth it into natural English.

## On the AP Exam

Multiple-choice questions love to point at a single gerundive and ask what it's doing. A typical stem reads "In the sentence, vitandum functions as..." and the credited answer identifies it as a gerundive in a passive periphrastic expressing necessity, not a gerund, participle, or supine. On the translation free-response questions, you have to render the construction literally and accurately. "Must be avoided" or "has to be avoided" earns credit; loosely paraphrasing as "they avoided it" does not, because it drops the necessity and the passive voice. Also watch for a dative noun nearby. If you translate it as an indirect object instead of the agent ("by/for whom it must be done"), you'll lose the sense of the clause.

## passive periphrastic vs Gerund

A gerund is a verbal NOUN ("the act of avoiding") that only appears in the singular oblique cases. A gerundive is a verbal ADJECTIVE that agrees with a noun and, when paired with sum, forms the passive periphrastic ("must be avoided"). Quick test: if the -nd- form agrees with a noun or sits next to a form of sum, it's a gerundive. If it stands alone as a noun, it's a gerund. AP multiple choice loves to put both in the answer options for a word like vitandum.

## Key Takeaways

- The passive periphrastic is a gerundive (-ndus, -nda, -ndum) plus a form of sum, and it expresses obligation or necessity, translated as "must be" or "has to be."
- The person who must do the action goes in the dative case (dative of agent), not the usual ab plus ablative used with normal passive verbs.
- The gerundive agrees with its subject in gender, number, and case, just like any other adjective.
- On multiple choice, expect questions asking what a form like vitandum "functions as," with gerund, participle, and gerundive all sitting in the answer choices.
- On translation questions, you must keep the construction literal: render necessity ("must be avoided"), keep it passive, and translate any dative as the agent.

## FAQs

### What is the passive periphrastic in Latin?

It's a construction made of a gerundive (the -ndus, -nda, -ndum verbal adjective) plus a form of sum that expresses necessity or obligation. Hoc faciendum est means "this must be done," and the classic example is Carthago delenda est, "Carthage must be destroyed."

### Is the passive periphrastic the same as a gerund?

No. The gerund is a verbal noun ("avoiding"), while the periphrastic uses a gerundive, a verbal adjective that agrees with a noun. AP multiple choice deliberately offers both as answer choices for forms like vitandum, so check whether the -nd- word agrees with a noun or pairs with sum. If it does, it's a gerundive.

### How do I translate the passive periphrastic?

Translate the gerundive plus sum as "must be" or "has to be" plus the verb's meaning, so vitandum est becomes "it must be avoided." If there's a dative noun, that's the agent: nobis vitandum est means "it must be avoided by us," or naturally, "we must avoid it."

### Why does the passive periphrastic use the dative instead of ab plus the ablative?

That's just the rule for this construction. Normal passive verbs take ab plus ablative for a personal agent, but the periphrastic takes a plain dative, called the dative of agent. Translating that dative as an indirect object instead of the agent is one of the most common errors on translation questions.

### Is the passive periphrastic on the AP Latin exam?

Yes. It appears in both Caesar's Gallic War and Vergil's Aeneid, the two required authors. Multiple-choice questions ask you to identify the grammatical function of gerundives like vitandum, and the literal translation free-response questions require you to render the necessity and the dative of agent accurately.

## Related Study Guides

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

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