Interrogative Adjective Qui, Quae, Quod

Interrogative quī, quae, quod accompanies a noun and asks the listener to identify, classify, or select its referent: quī liber? “which book?”, quae via? “which road?”, quod cōnsilium? “what plan?” It is called an interrogative adjective because it agrees with the noun it modifies in gender, number, and case.

Its forms are identical to the relative pronoun quī, quae, quod. Function, not spelling alone, tells them apart. An interrogative opens a request for information; a relative links a referring expression to a subordinate clause. English often translates both with “which,” so a sound Latin parse must begin from clause structure. Review the linking use on Relative Pronoun Quī, Quae, Quod.

The complete paradigm

The paradigm is pronominal rather than an ordinary first-and-second-declension adjective: note singular genitive cuius and dative cui. The other forms largely resemble the relative paradigm. All are normal in neutral and formal Classical prose.

Agreement requires three separate observations. The noun supplies gender and number; the noun phrase's role supplies case; the speaker's discourse goal supplies the interrogative force. Do not choose quī merely because the English begins with “which.”

Liber is masculine singular and the subject of est, so the interrogative is nominative masculine singular quī.

Viam is feminine singular and the direct object of sequimur, so its modifier is accusative feminine singular quam.

Dōna is neuter plural accusative. Neuter plural quae agrees in all three features.

“Which?” and “what kind of?”

The adjective interrogative commonly selects a member of a known or imaginable set. A speaker asking quī liber? assumes that books are available for identification; quis? alone instead asks who or what the unknown entity is. Context can also give quī a qualitative sense, “what sort of?”

The first question selects a shop from a contextual set. The second can ask either which available wine or what kind of wine. Latin does not mechanically mark that pragmatic difference; situation and emphasis do the work.

In a rhetorical question (oratorical/formal), quī vir classifies character rather than requesting a name. Compare neutral substantive quis hoc fēcit? “Who did this?” The forms express a viewpoint: the speaker can ask for bare identity, a choice from a set, or an evaluative type.

Case across the noun phrase

Like any agreeing adjective, the interrogative follows the entire noun phrase into whatever case syntax requires. Prepositions and case-governing verbs are especially useful diagnostics.

The recipient is dative, so both cui and discipulō are dative singular masculine.

Time when uses the ablative without a preposition. Masculine singular diēs therefore appears as diē, with ablative quō.

Here dē governs the ablative phrase quā causā. The order quā dē causā places the preposition between modifier and noun, a common Latin arrangement (neutral/formal); dē quā causā is also possible.

The interrogative modifies genitive poētae, not accusative carmina, so it is genitive singular cuius. Ask which word it belongs with before matching an ending to the nearest visible noun.

Singular and plural choices

Number reflects what alternatives the speaker is asking the listener to identify. Singular quem librum? expects one book; plural quōs librōs? asks for more than one. A collective answer does not automatically make the interrogative singular.

In the second example quārum modifies feminine plural urbium. The subject is moenia, but that does not control quārum: the genitive phrase means “the walls of which cities.”

Interrogative or relative?

Since the two paradigms are identical, look beyond the isolated form.

This is an indirect question: the road remains unknown within the reported question, and īret is subjunctive. By contrast, via quā ad forum iit means “the road by which he went to the forum”; there quā is relative and its antecedent is via.

The useful but imperfect quis/quī contrast

A practical starting rule is:

• substantive quis? quid? = “who? what?” with no expressed head noun;
• adjective quī? quae? quod? = “which/what?” agreeing with an expressed noun.

Actual Classical usage overlaps. Quis homō? and quis diēs? are common, especially where the question is strongly about identity; quī? can stand alone when an omitted noun is obvious. This is not carelessness. The two interrogative patterns come from the same pronominal system, and discourse purpose can outweigh a tidy classroom boundary.

Here adjectival quis with a person noun is idiomatic (neutral). A learner should recognize it, while using regular agreement quī amīcus, quae fēmina, quod dōnum as the safest productive pattern when explicitly modifying nouns.

Word order and focus

The interrogative phrase often comes first, but Latin word order is not a question-forming rule. Moving the phrase can mark contrast or create suspense, especially in oratory and poetry (formal/literary).

Initial tū autem establishes a contrastive addressee before the unknown plan. What makes the phrase interrogative is quod plus the discourse context, not obligatory first position. In neutral composition, placing the interrogative phrase early usually makes the question easiest to process.

Common Mistakes

Using substantive quid before an expressed noun

Neuter iter requires nominative singular adjective quod.

Matching English “which” instead of the Latin case

The English question word does not change, but Latin quī must become accusative quem with medicum.

Agreeing with the wrong noun

The interrogative belongs inside the genitive phrase cuius poētae.

Assuming every qui is relative

The form quī is interrogative here; the unresolved embedded question requires sit.

Using uter for more than two choices

For a two-member contrast, uter is precise; for an unrestricted or larger set, use quī.

Key Takeaways

• Quī, quae, quod agrees with its expressed noun in gender, number, and case.
• It can ask for selection (“which?”) or classification (“what kind of?”).
• The same forms are relative; clause function and discourse context distinguish them.
• Direct questions do not require English-style inversion; indirect questions normally use the subjunctive.
• Quis sometimes modifies person nouns, but regular adjectival agreement remains the clearest productive pattern.