Overview
The first and second declensions contain the largest group of Latin nouns and adjectives, and they are the base of term formation. This revision covers their endings, the agreement of adjectives, and the adjective suffixes.
Nouns of the first and second declensions
First-declension nouns end in -a (genitive -ae) and are mostly feminine: vena, -ae f. Second-declension nouns end in -us or -er (masculine) and -um or -on (neuter), with the genitive in -i: nervus, -i m; cancer, -cri m; ligamentum, -i n; ganglion, -i n. In neuter nouns the nominative and accusative are always the same, and the plural ends in -a.
A few masculine nouns belong to the first declension (collega, -ae m), and some Greek feminine nouns in -e have the genitive -es (acne, -es f).
Adjectives of the first and second declensions
Adjectives in -us, -a, -um decline like the nouns of the first and second declensions and agree with their noun in gender, number and case: vena magna, nervus medianus, ligamentum latum.
Adjectives in the first and second declension change in gender, number, and case.
These adjectives agree with the nouns they modify in gender, number, and case but differ in endings. This is called a coordinated attribute.
Some adjectives can be used as nouns: rectum, caecum, arachnoidea, and vagus.