1. Essentials at a Glance

Fourth Declension nouns in Latin grammar generally feature a stem ending in -u- and a genitive singular in -ūs. Most are masculine and end in -us in the nominative (e.g. frūctus, “fruit”) while a handful are feminine (e.g. manus, “hand”) or neuter (e.g. cornū, “horn”). They occur frequently in literary, historical, and legal texts. Mastery of these forms is essential for accurate reading and translation, as they appear in both concrete and abstract vocabulary.

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2. Definition & Importance

The Fourth Declension in Latin grammar comprises nouns typically marked by -us or -ū endings, with the genitive singular -ūs. These words include everyday terms like domus (“house”) and manus (“hand”), as well as abstract nouns like impetus (“attack”) or metus (“fear”).

Understanding the Latin Fourth Declension examples is crucial for correct syntax, morphology, and reading comprehension. Frequent words like senātus (“Senate”) and exercitus (“army”) highlight its importance in historical and political contexts. Recognizing common errors in the Fourth Declension—such as confusing its genitive (-ūs) with the second declension (-ī)—helps learners avoid misinterpretations in classical texts.

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3. Forms & Morphology

Below are two standard paradigms illustrating the Fourth Declension forms. Most masculine/feminine nouns use an -us nominative, while neuters end in -ū.

Key notes:

• A few nouns (e.g. domus, “house”) exhibit mixed forms (sometimes borrowing endings from the second declension).
• Feminine nouns include manus (“hand”) and porticus (“portico”).
• Neuter nouns like cornū and genū have plural endings in -ua (cornua, genua).
• Some words allow -ubus in the dative/ablative plural (e.g. arcubus, “to/with bows”) instead of -ibus.

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4. Usage & Examples

Fourth Declension nouns follow normal Latin case rules. They commonly denote concrete items, actions/results of verbs (e.g. cursus from currere, “to run”), or collective bodies (e.g. senātus).

1. Cicero: “Habēmus senātūs cōnsultum...”

• “We have a decree of the Senate...”
• senātūs (gen. sg.) modifies cōnsultum (“decree”), emphasizing the Senate’s authority.

2. Caesar: “Ad dextrum cornū profectus...”

• “Having set out to the right wing...”
• cornū (acc. sg. neuter) = “wing” of the army; literally “horn.”

3. Horace (Odes): “... gelūque flūmina cōnstitērint acūtō.”

• “... and the rivers have frozen solid with sharp frost.”
• gelū (abl. of means) = “by/with frost.”

4. Livy: “Prīmō impetū urbem capere cōnātī sunt.”

• “They tried to capture the city in the first assault.”
• impetū (abl. sg.) = “by/with an attack.”

5. Tacitus: “Nē iniussū Caesaris discēderent.”

• “That they not depart without Caesar’s command.”
• iussū (abl. sg. meaning “by order”) is found mostly in this fixed ablative form.

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5. Common Pitfalls

• Mistaking Endings: Confusing fourth declension -ūs with second declension -ī. Check context and macrons carefully.
• Domus Variations: Domus mixes forms from the second and fourth declensions (e.g. domī “at home,” domum “(to) home,” domō “from home”).
• Gender Errors: Words like manus or porticus are feminine despite their -us ending.
• Plural vs. Genitive Overlap: -ūs can be either a plural nominative/accusative or a genitive singular (e.g. senātūs). Context is key.

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6. Additional Notes & Nuances

Fourth Declension nouns are often verbal derivatives, expressing actions or results (impetus, cantus, cursus). Some form part of idiomatic phrases—such as manūs dare (“to surrender”) or manūs cōnserere (“to join battle”).

A few exhibit archaic or poetic forms in early Latin (e.g. genitive -ī for senātī). Poets also favor them for their long -ū endings, which fit certain meters. Rarely, alternative endings like -ubus appear for the dative/ablative plural (e.g. arcubus, lacubus).

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7. Key Takeaways

• Recognize -ūs endings: These signal the fourth declension (gen. sg. or nom./acc. pl.).
• Memorize irregulars: Especially domus and the feminine nouns (e.g. manus).
• Watch for neuter -ū: Plural in -ua (e.g. cornua).
• Check context: Many forms overlap. Use surrounding words (adjectives, prepositions) to clarify.
• Beware special ablatives (iussū, nātū, iniussū), often used adverbially.