The Five Declensions at a Glance

Latin's five declensions are five families of noun inflection. A declension tells you which set of case-and-number forms a noun uses; it does not by itself tell you the noun's syntactic function, meaning, or gender. The reliable family label is the genitive singular: -ae, -ī, -is, -ūs, or fifth-declension -eī/-ēī. In that last ending, e is long between vowels (diēī) but short after a consonant (reī).

English changes most nouns only for plural and possession. Latin changes a noun for six core cases in singular and plural, so learning “rēx means king” is not enough. Learn rēx, rēgis m.: the genitive identifies the third declension and reveals rēg-; the gender controls agreement. The genitive-and-gender method turns that entry into a repeatable vocabulary routine. All paradigms below represent neutral Classical Latin.

The identifying map

The stem-type names explain historical structure; they are not always a mechanical instruction to cut the same number of letters from every genitive. The safest beginner procedure is to identify the declension from the genitive ending, then learn how that family combines its base, characteristic vowel, and endings. For third-declension consonant stems, removing -is is especially useful: rēg-is gives rēg-.

Complete model paradigms

This table gives all six cases in both numbers for one non-neuter model from each declension. A slash separates singular from plural.

Several forms coincide. Puellae has four possible analyses; servō is dative or ablative singular; rēs can be nominative singular or nominative, accusative, or vocative plural. A paradigm supplies possible forms, not an automatic interpretation. Syntax, agreement, and context decide among them.

The first puella is nominative singular; amīcae is dative singular because the friend is the recipient. The same ending -ae can therefore express different feature bundles within one sentence.

Nominative rēx is the subject, while accusative plural lēgātōs is the direct object. Position supports the ordinary reading here, but the endings establish it.

Fourth-declension manus is nominative singular; dative mihi expresses the person affected. Do not classify manus as second declension merely because it ends in -us.

Both rēs, reī f. and spēs, speī f. are fifth declension. Their singular paradigms are productive Classical forms, but only rēs and diēs have fully attested paradigms throughout both numbers; many other fifth-declension nouns lack some or all plural forms.

The neuter rule across declensions

First and fifth declensions have no regular native neuter class. Second, third, and fourth declensions do. Across all of them, the nominative, accusative, and vocative are identical, and those three cases end in short -a in the plural; third-declension i-stems have -ia, which still ends in short a.

The following table gives complete neuter paradigms. The oblique cases still reveal each noun's declension.

In each sentence the plural -a form is neuter. English plural -s offers no help here; learners must internalize the Latin neuter pattern.

What each declension predicts—and what it does not

The first declension is highly productive for feminine nouns, but male occupational nouns such as agricola m. “farmer,” nauta m. “sailor,” and poēta m. “poet” take masculine agreement. The second has a strong form-and-gender correlation, yet lexical exceptions exist. The third is the most diverse: its nominative may conceal the stem, and both gender and the consonant-stem versus i-stem pattern require dictionary information.

The fourth is smaller. Most nouns in -us are masculine, but high-frequency manus and domus are feminine; domus also mixes second- and fourth-declension forms. The fifth is smallest and often defective in the plural. These are lexical facts, not failures of the case system.

Masculine perītus agrees with first-declension nauta. The preposition in takes accusative portum because the sailor is moving toward the harbor; neither the noun's first-declension endings nor its position supplies its gender.

Rare inherited endings occur in early texts (archaic), and poets sometimes use contracted or Greek-shaped alternatives (literary). Those forms belong on specialized pages. For ordinary production, use the regular Classical paradigms above.

Parsing in four moves

When you meet an inflected noun, do not translate the first familiar-looking form immediately:

1. Recover the dictionary entry, especially its genitive and gender.
2. Identify the declension from the genitive ending.
3. List the case-and-number values that the visible ending can carry.
4. Use agreement, prepositions, and the verb's argument structure to select the function.

Long -ūs excludes nominative singular manus, but it still permits several analyses. The singular imperative needs a direct object, so manūs is accusative plural here.

Common Mistakes

1. Guessing declension from the nominative alone

The genitive manūs supplies the decisive marker -ūs.

2. Building third-declension forms on the nominative

The entry rēx, rēgis reveals rēg-; the nominative reflects a sound change at the stem boundary.

3. Treating every first-declension noun as feminine

The ending identifies a declension, while the dictionary label identifies gender.

4. Giving a neuter plural a masculine accusative ending

Neuter nominative, accusative, and vocative plurals end in short -a; agreeing multa follows the same feature bundle.

5. Inventing a third-declension genitive for a fifth-declension noun

The learned entry is rēs, reī f.; genitive -eī identifies the fifth declension.

Key Takeaways

The five genitive singular markers—-ae, -ī, -is, -ūs, and fifth-declension -eī/-ēī—organize the noun system. A model paradigm shows how each family marks case and number, but gender remains lexical and visible endings are often ambiguous. Learn every noun with genitive and gender, apply the universal neuter rule, and let syntax select among forms that a table alone cannot disambiguate.