2.  Some other peculiarities occur, especially in poetry.

* * * * *

SECOND DECLENSION.

o-Stems.

23.  Pure Latin nouns of the Second Declension end in -us, -er, -ir, Masculine; -um, Neuter.  Originally -us in the Nominative of the Masculine was -os; and -um of the Neuters -om.  So also in the Accusative.

Nouns in -us and -um are declined as follows:—­

Hortus, garden; Bellum, war;
stem, horto-. stem, bello-. 
SINGULAR. 
TERMINATION.  TERMINATION.
Nom. hortus -us bellum -um
Gen. horti -i belli -i
Dat. horto -o bello -o
Acc. hortum -um bellum -um
Voc. horte -e bellum -um
Abl. horto -o bello -o

PLURAL.
Nom.  horti        -i      bella        -a
Gen.  hortorum     -orum   bellorum     -orum
Dat.  hortis       -is     bellis       -is
Acc.  hortos       -os     bella        -a
Voc.  horti        -i      bella        -a
Abl.  hortis       -is     bellis       -is

Nouns in -er and -ir are declined as follows:—­

Puer, boy;     Ager, field;  Vir, man;
stem, puero-     stem, agro-     stem, viro-
SINGULAR.                          TERMINATION.
Nom.  puer             ager            vir               Wanting
Gen.  pueri            agri            viri            -i
Dat.  puero            agro            viro            -o
Acc.  puerum           agrum           virum           -um
Voc.  puer             ager            vir               Wanting
Abl.  puero            agro            viro            -o

PLURAL.
Nom.  pueri            agri            viri            -i
Gen.  puerorum         agrorum         virorum         -orum
Dat.  pueris           agris           viris           -is
Acc.  pueros           agros           viros           -os
Voc.  pueri            agri            viri            -i
Abl.  pueris           agris           viris           -is

1.  Note that in words of the type of puer and vir the final vowel of the stem has disappeared in the Nominative and Vocative Singular.

In the Nominative and Vocative Singular of ager, the stem is further modified by the development of e before r.

2.  The following nouns in -er are declined like puer:  adulter, adulterer; gener, son-in-law; Liber, Bacchus; socer, father-in-law; vesper, evening; and compounds in -fer and -ger, as signifer, armiger.

Nouns in _-vus_, _-vum_, _-quus_.

24.  Nouns ending in the Nominative Singular in -vus, -vum, -quus, exhibited two types of inflection in the classical Latin,—­an earlier and a later,—­as follows:—­