Gerund, Gerundive & Supine
Latin has three special verb-derived forms that aren't participles and aren't infinitives. The gerund is a verbal noun — the -ing form: amandī ("of loving"), amandō ("by loving"), amandum ("the act of loving"). The gerundive is a verbal adjective — passive: liber legendus ("a book to be read"). The supine is a fossilized verbal noun stuck in two cases: -um for purpose after motion verbs (īt vīsum — "he goes to see"), -ū for respect (facile dictū — "easy to say").
Here's the trap that derails everyone: the gerund and the gerundive look identical (both end in -ndus, -nda, -ndum) — but one is a noun and the other is an adjective.
Cōnsilium urbis capiendae and cōnsilium urbem capiendī both mean "a plan of taking the city," but the first uses the gerundive (agreeing with urbis) and the second uses the gerund (with a direct object).
Latin almost always picks the gerundive when there's an object in play.
Three different forms, all built off the verb stem, each filling a slot the infinitive can't quite reach.
Gerund and gerundive look IDENTICAL — gerund is a NOUN (no agreement), gerundive is an ADJECTIVE (always agrees with something). Latin prefers the gerundive whenever an object is present.
See It In Action
— Cic. De Or. ii. 157
Both -ndī forms are gerunds (nouns in the genitive). Diiūdicandī even keeps an accusative object (vēra ac falsa) — that's the verbal force of the gerund showing through. With ANY other object Latin would switch to the gerundive.
— Cic. Cat. i. 4
Cicero could have said ad dēpōnendum audāciam (gerund + acc.) — but he doesn't, because Latin almost always swaps in the gerundive when an object is in play. Dēpōnendam and cōnfirmandam are adjectives agreeing with audāciam.
— Liv. iii. 25
This is the supine in -um in its purest form: a motion verb (vēnērunt), then -um expressing what they came TO DO. The supine even keeps its verbal force enough to take an accusative object (iniūriās).
— Cic. Phil. ii. 63
The -ū supine almost always pairs with an adjective like foedus, facilis, difficilis, dignus and answers "in WHAT respect?" — never takes an object. Memorize the short list: audītū, dictū, factū, vīsū.
"the act of X-ing" / "X-ing" as an English verbal noun
ars disserendī = "the art of discoursing" (gen. of the gerund)
translate ACTIVELY in English even though Latin is passive
ad pācem petendam = "to seek peace" (literally "for peace to be sought")
"X must be V-ed" / "X has to be V-ed"; agent in dative if named
mihi liber legendus est = "the book must be read by me / I must read the book"
"to V" / "in order to V" — only after motion verbs
īt vīsum = "he goes to see"; cubitum dīscēdunt = "they leave to sleep"
"to V" / "in respect of V-ing" — locks the adjective's domain
facile dictū = "easy to say"; mīrābile vīsū = "wondrous to see"
Identical endings (-ndus, -nda, -ndum) — but one is a noun standing alone, the other is an adjective agreeing with something.
neut. sg., active, no agreement
cōnsilium urbem capiendī
a plan of taking the city (gerund + acc. obj. — rare)
all genders, passive, agrees
cōnsilium urbis capiendae
a plan of (the city) being taken (gerundive agrees with urbis)
Tip: Look for agreement. If the -nd- form matches a noun's gender/number/case nearby, it's a gerundive. If it stands alone in the genitive/dative/accusative/ablative singular neuter, it's a gerund. When an object is in play, Latin picks gerundive 95% of the time.
In cōnsilium urbis capiendae ("a plan of taking the city"), what is capiendae?
Study Tips
- •Read every -ndus form twice: first ask "what noun is this agreeing with?" If it agrees, it's a gerundive (adjective). If it stands alone in the genitive/dative/accusative/ablative, it's a gerund (noun).
- •Memorize the supine in -ū short list — audītū, dictū, factū, vīsū, memorātū — and recognize the facile / difficile / fās / nefās + supine pattern at sight.
- •When you see ad + -ndum/-ndam/-ndōs, expect purpose ("in order to X"). When you see causā / grātiā with a genitive -ndī/-ndae, also purpose. Two different ways to say the same thing.
- •Drill the passive periphrastic separately: gerundive + sum is the obligation construction (Carthāgō dēlenda est — "Carthage must be destroyed"). Same form, different syntactic life.