vocativus

Vocativus, or the vocative case, is a grammatical case in Latin used for direct address. It marks when the speaker calls someone by name, title, or epithet, and it is often accompanied by an interjection such as O in writing. In everyday Latin, the vocative is typically the form you would use when you speak directly to a person or thing.

In many nouns, the vocative closely mirrors the nominative, especially in the third declension and for neuter nouns. The most noticeable regular exception occurs in the masculine singular of the second declension, where the ending -us of the nominative often becomes -e in the vocative (for example, dominus becomes domine; Marcus becomes Marce). Other second-declension -us nouns behave similarly, while some retained forms exist in poetry or certain registers. First-declension feminine nouns and neuter nouns generally keep the nominative form in the vocative, so puella remains puella and templum remains templum in direct address. In the third declension, many nouns also keep the nominative form in the vocative (rex, pater, civis), though there are occasional irregularities, especially with proper names of certain origins or historical usage.

Beyond morphology, the vocative is distinguished in function by its syntactic role: it is the direct address, often invoking a sense of immediacy or emphasis in speech or prose. It is used across ages of Latin literature, from formal letters to classical poetry, and may appear with an introductory interjection such as O to heighten the direct address.

Overall, vocativus is one of the primary devices for signaling direct speech in Latin, with patterns that are predictable for many nouns and notable exceptions that must be learned.