ablativus

The ablativus, or ablative case, is one of the core grammatical cases in Latin. It covers a broad range of adverbial and nominal relations. Often it marks means, manner, or the agent of an action, but it also expresses source or separation, accompaniment, place from which, time, price, degree, and other abstract relations. In many phrases the ablative stands without a preposition, while in others it is introduced by common prepositions such as cum, a/ab, ex/e, de, in, or per.

Among its primary uses, the instrument or means is a central function: the ablative names the tool with which an action is performed, for example gladio pugnare “to fight with a sword.” Manner and degree can appear in the bare ablative or with cum, as in magna voce or magna cum laude. Accompaniment is expressed with cum: venit cum amicis. The agent in passive clauses is marked by a/ab: a Caesare laudatus est “he was praised by Caesar.”

Other frequent uses include source or separation (ex urbe, de monte), place from which (often with prepositions), time expressions and duration (tribus diēbus “for three days”), price or value (duā denariīs), and degree of difference (tantō, plūs, etc.). The ablative also appears in expressions of cause or reason in certain idioms, including fear or motive with nouns like timore.

Declension and form: the endings of the ablative vary by noun declension. Common patterns include: 1st declension singular -ā, plural -īs; 2nd declension singular -ō, plural -īs; 3rd declension singular -e (or -ī for some i-stems), plural -ibus; 4th declension singular -ū, plural -ibus; 5th declension singular -ē, plural -ēbus. The exact ending depends on the noun's stem and declension.