General characteristics of the second declension
The second declension includes masculine and neuter nouns that historically have an -o- stem. In Nominativus singularis, masculine nouns end in -us or -er, and neuter nouns end in -um.
The sign of belonging to the second declension is the Genetivus singularis ending -i. It is precisely the genitive form that determines the declension of a noun in Latin.
Examples of second-declension words:
- dominus — master (m.);
- liber — book (m.);
- campus — field (m.);
- infusum — infusion (n.);
- folium — leaf (n.).
Gender exceptions
Despite the typical -us ending, a number of nouns belong to the feminine gender and must be memorized:
- bolus — clay;
- crystallus — crystal;
- alvus — belly / bowels.
A separate group of exceptions consists of nouns in -us denoting tree names: regardless of their declension, they are always feminine. Examples: alnus — alder, amygdalus — almond, eucalyptus — eucalyptus.
Case ending paradigm
Endings of second-declension nouns by case and number:
- Nom. sg.: -us, -er (m.), -um (n.);
- Gen. sg.: -i (for all genders);
- Dat. sg.: -o;
- Acc. sg.: -um (m. and n.), less commonly -on (borrowings from Greek);
- Abl. sg.: -o;
- Nom./Acc. pl.: -i (m.), -a (n.);
- Gen. pl.: -orum;
- Dat./Abl. pl.: -is;
- Acc. pl. m.: -os.
Declension examples: musculus, musculi (Gen. pl. musculorum); folium, folii (Gen. pl. foliorum); ligamentum in Dat. sg. — ligamento, Dat. pl. — ligamentis; nervus in Acc. sg. — nervum, Acc. pl. — nervos; ganglion in Acc. sg. — ganglion, Acc. pl. — ganglia.
Features of words in -er
Masculine nouns ending in -er in most cases lose the vowel -e- in the stem when declined in oblique cases. For example: ager — agri (field). However, in some words the letter -e- is retained: puer — pueri (boy). Belonging to one group or the other is determined by the form of Genetivus singularis.
Vocativus and its features
In nouns and adjectives of all declensions in both numbers, Vocativus coincides with Nominativus. For example: vesper — Voc. sg. vesper, Voc. pl. vesperi; decoctum — Voc. sg. decoctum, Voc. pl. decocta.
An exception is made by masculine nouns in -us: their Vocativus singularis ends in -e. For example: dominus — Voc. sg. domine. For words in -ius, the Vocativus singularis ends in -i: filius — Voc. sg. fili.
Drug names
All drug names in Latin belong to the second declension, are of neuter gender, end in -um in Nominativus singularis, and in -i in Genetivus singularis. Into Russian, such names are not translated but transcribed — rendered in Russian letters without the -um ending. For example: Analginum — analgin, Validolum — validol. This pattern is fundamentally important for writing a prescription line.
Key points
- The second declension combines masculine nouns in -us, -er and neuter nouns in -um.
- The sign of declension is the Gen. sg. ending -i.
- The words bolus, crystallus, alvus are feminine exceptions.
- All tree names in -us are feminine regardless of declension.
- Words in -er more often lose -e- when declined (ager — agri), but puer retains it.
- Vocativus coincides with Nominativus, except for forms in -e (domine) and -i (fili).
- Drug names are always neuter of the second declension with the ending -um.
- Plural endings: Gen. -orum, Dat./Abl. -is, Acc. -os/-a.