First declension

The first declension is the a-declension: its nouns have the stem vowel -a. Learn these ten points first.

1. The dictionary form ends in -a and the genitive singular ends in -ae. Both tell you that a noun belongs to the first declension.
2. About 90 per cent of first declension nouns are feminine. A few are masculine, such as collega, ae m (colleague) and the Greek words ascites and diabetes.
3. Singular endings: nominative -a, genitive -ae, accusative -am.
4. Plural endings: nominative -ae, genitive -arum, accusative -as.
5. The same spelling -ae is the genitive singular and the nominative plural. Decide the number from the sentence, not from the spelling.
6. The stem is the genitive minus -ae: vena, ae f (vein) has the stem ven-.
7. Greek loanwords in the first declension have a nominative in -e (acne) with genitive -es (acnes), or a masculine nominative in -es (ascites) with genitive -ae.
8. In a noun + noun term, the second noun goes into the genitive singular: fractura mandibulae = fracture of the lower jaw. The first noun does not change.
9. An adjective in the feminine nominative singular -a (acutus, a, um gives acuta) also belongs to the first declension and agrees with its noun: anaemia acuta = acute anaemia.
10. Read every term by substitution and practise until you know the meaning without the table.

How to recognise it: Nominative ends in -a -> feminine (about 90 per cent) -> genitive ends in -ae -> stem = genitive minus -ae (venae gives ven-) -> use the endings table in section 2.

The first declension is characterised by the stem ending "-a". It contains nouns and adjectives that are usually feminine, for example vena (vein) and acuta (acute). The stem letter of the nouns is a. The nominative singular ends in -a and the genitive singular ends in -ae.

Some masculine nouns, generally referring to occupations, also belong to the first declension, for example collega, ae m (colleague). The ways of indicating the meanings of words are conventions, so meaning is determined in a term by substituting simple formulas. Sometimes there are small variations or exceptions to these formulas.

The purpose of studying these tables is to help you distinguish the inflected forms automatically and effortlessly. Practise the exercises until you can recognise the meaning without having to recall the declension table.

The endings of the first declension are the same for every noun in it. Read the table across for the case and down for the number.

Note the trap in the table: the genitive singular and the nominative plural are both spelled -ae. In vena, venae is genitive singular ("of the vein") and nominative plural ("veins").

The dative and ablative are needed for the expressions in section 7 and are written here from standard textbook Latin.

Each noun below ends in -a in the nominative singular and in -ae in the genitive singular, and is feminine. The genitive is written in full.

Some words are taken from Greek and keep their Greek endings in the nominative. They are still first declension nouns, and the rest of their endings follow the Latin pattern. Read the gender and the genitive from the dictionary form.

Greek feminine: the nominative ends in -e and the genitive in -es. Examples: acne, acnes; diastole, diastoles; systole, systoles.

Greek masculine: the nominative ends in -es and the genitive in -ae. Only two words are of this kind: ascites, ae m and diabetes, ae m.

In a term made of two nouns, the noun in the genitive singular gives the "of" meaning. The rule has two parts:

1. The first noun does not change. Its form does not matter: fractura is the same in every example below.
2. The second noun has to be in the genitive singular. A first declension second noun ends in -ae: mandibula gives mandibulae.

Example: fractura mandibulae = fracture of the lower jaw.

More examples of the same pattern, with their English.

After the preposition post, the noun takes the accusative, so post fracturam is correct: fracturam is accusative singular.

These terms show the first declension nouns and adjectives working together. The adjectives agree with their noun in case, number and gender.

Notice that ulna dextra and ulna sinistra use the feminine adjectives dextra and sinistra, because ulna is feminine. The same is true of tuba auditiva and tuba uterina.

These short expressions use the first declension in the ablative, and the preposition before them.

Menopausa and epilepsia are ablative singular forms, ending in -a as in the table above.

An adjective whose feminine nominative singular ends in -a belongs to the first declension. The adjective agrees with its noun in gender, number and case.

If every word in a term belongs to the first declension, they all change together in the same way. Example: Anaemia acuta, in the genitive singular, becomes anaemiae acutae.

• Singular: -a, -ae, -am (nominative, genitive, accusative).
• Plural: -ae, -arum, -as (nominative, genitive, accusative).
• The genitive singular and the nominative plural are both -ae.
• About 90 per cent of first declension nouns are feminine; collega is masculine.
• Stem = genitive minus -ae: ven- from venae.
• Greek feminine: nominative -e, genitive -es (acne, acnes). Greek masculine: nominative -es, genitive -ae (ascites, ascitae).
• Noun + noun: the second noun goes into the genitive singular: fractura mandibulae.
• Feminine adjective in -a agrees with its noun: anaemia acuta.

Q: Nominative singular ending of the first declension? A: -a, as in vena. Q: Genitive singular of vena? A: venae. Q: Genitive plural of vena? A: venarum. Q: Accusative singular of vena? A: venam. Q: Accusative plural of vena? A: venas. Q: Which two cases are both -ae? A: Genitive singular and nominative plural. Q: Stem of vena, ae f? A: ven-. Q: Gender of most first declension nouns? A: Feminine, about 90 per cent. Q: Genitive singular of mandibula? A: mandibulae. Q: Translate fractura mandibulae. A: Fracture of the lower jaw. Q: Translate anaemia acuta. A: Acute anaemia. Q: Nominative and genitive of the Greek feminine acne? A: acne, acnes. Q: Genitive singular of the Greek masculine ascites? A: ascitae. Q: Translate Tuba auditiva. A: Auditory (Eustachian) tube. Q: Genitive singular of collega, a masculine noun of this declension? A: collegae.