The Supine in -u

The supine in -ū is a rare verbal noun used chiefly after an adjective of evaluation: facile dictū means “easy to say,” literally “easy with respect to saying.” Its form is the ablative singular of the same fourth-declension verbal noun whose accusative in -um expresses purpose after a verb of motion. It has no tense contrast, never agrees with another word, and belongs chiefly to concise (formal/literary) Classical prose.

English encourages an immediate infinitive translation—“easy to see”—but that translation conceals the Latin structure. First locate the adjective being qualified, then ask whether the -ū form names the action with respect to which the evaluation holds.

Formation: the Supine Stem plus -ū

The form comes from the fourth principal part traditionally called the supine. Remove -um and add ablative -ū. Because the vocabulary is restricted, however, a mechanically possible form is not automatically idiomatic Classical Latin.

The long -ū matters: dictū is ablative, whereas dictum may be the accusative supine or a neuter perfect passive participle. The stem itself can be irregular: faciō gives factū, not faciendū. That latter-looking sequence belongs to the gerund or gerundive system, not the supine.

The Core Construction: an Ablative of Respect

The -ū supine restricts an adjective: easy in what respect? wonderful to do what? It supplies neither the clause's subject nor a separate event on a timeline.

In these examples, cōnsilium or nārrātiō is the subject of est or vidētur. The supine is an ablative dependent on the evaluative adjective. It does not agree with that subject: feminine nārrātiō still has invariant audītū.

The construction is close to an ablative of respect such as clārus factīs “famous in deeds.” Its verbal origin remains visible because dictū evokes “saying” and factū evokes “doing,” but the syntax is nominal.

Typical Adjectives and a Restricted Vocabulary

Frequent governing adjectives include facilis “easy,” difficilis “difficult,” iūcundus “pleasant,” mīrābilis “wonderful,” incrēdibilis “incredible,” horribilis “terrible,” and foedus “shameful.” Frequent supines include dictū, factū, vīsū, audītū, cognitū, and memorātū. Expressions such as mīrābile dictū and horribile vīsū can become almost formulaic (literary) phrases.

Livy contrasts the supine with an ordinary ablative of respect in a compact authentic phrase:

Here dictū supplies the action with respect to which something is easier, while rē contrasts the reality or execution of it.

The adjective carries the evaluation; the supine names its domain. Consequently, mīrābile dictū does not assert that anyone actually told the story. It says that the content would be remarkable considered as something told.

Classical prose does not treat the construction as a productive substitute for every English “adjective + to-infinitive.” For “ready to write,” for example, Latin may use a participle, a relative clause, or ad with a gerund, depending on meaning. Memorizing the common combinations is unavoidable.

Voice and Relative Time

The -ū supine is normally translated with an English passive-like infinitive when the evaluated thing would be the object of the action: liber facilis lectū is “a book easy to read.” Traditional grammars therefore often call its meaning passive. Yet the Latin form marks no voice ending and names an action abstractly. Its surrounding relation supplies the apparent patient.

Here litterae is grammatically the nominative subject of erant and semantically what one reads. There is no expressed agent and no agreement between plural litterae and lectū.

The supine also has no present, perfect, or future paradigm. Its action is interpreted relative to the evaluation. In litterae difficilēs lectū erant, the difficulty and the contemplated reading belong to the same relevant situation; the form itself does not say whether a reading was completed.

Minimal Contrast with the Supine in -um

The two supines share a stem but occupy different clause slots.

In the first sentence, accusative vīsum depends on the motion verb vēnērunt and expresses the scouts' purpose. In the second, ablative vīsū depends on difficilis and gives the respect in which the place was difficult. The first construction has an understood agent controlled by the subject of the motion verb; the second evaluates locus and need not identify an agent.

For the purpose construction, see The Supine in -um. For a full comparison with -nd- forms, see Gerund, Gerundive, or Supine?.

A Parsing Procedure

When you encounter a form in -ū, proceed from Latin structure rather than the first plausible English infinitive.

1. Confirm a supine stem: connect vīsū with vīsum, dictū with dictum.
2. Look for an adjective of evaluation such as facilis, mīrābilis, or horribilis.
3. Ask “easy, remarkable, or horrible with respect to what action?”
4. Keep the supine invariant; find agreement elsewhere, especially between the adjective and its noun.
5. Only then choose natural English, often “to be seen/said/done” or simply “to see/say/do.”

Plural neuter haec verba controls plural sunt and plural turpia. The invariant memorātū answers “shameful with respect to what?” Reading it as an adjective agreeing with verba would leave both its long -ū and the existing predicate adjective unexplained.

Common Mistakes

Treating the supine as an agreeing adjective

Using -um after an adjective

Inventing an agent or a completed event

Forming the supine from the present stem

Key Takeaways

• The supine in -ū is an invariant ablative verbal noun formed from the supine stem.
• It chiefly qualifies an adjective of evaluation and expresses the action “with respect to which” that evaluation holds.
• It has no tense, person, number, or agreement and is often passive-like only by interpretation.
• The construction is restricted (formal/literary) vocabulary, not a freely productive equivalent of every English “to” infinitive.
• Contrast adjective + -ū (respect) with motion verb + -um (purpose).