3. Indeclinable nouns, also infinitives and phrases, are Neuter; as,—
nihil, nothing; nefās, wrong; amāre, to love.
NOTE.—Exceptions to the above principles sometimes occur; as, Allia (the river), f.
B. Gender determined by Ending of Nominative Singular.
The gender of other nouns is determined by the ending of the Nominative Singular.[[11]]
NOTE 1.—Common Gender. Certain nouns are sometimes Masculine, sometimes Feminine. Thus, sacerdōs may mean either priest or priestess, and is Masculine or Feminine accordingly. So also cīvis, citizen; parēns, parent; etc. The gender of such nouns is said to be common.
NOTE 2.—Names of animals usually have grammatical gender, according to the ending of the Nominative Singular, but the one form may designate either the male or female; as, ānser, m., goose or gander. So vulpēs, f., fox; aquīla, f., eagle.
NUMBER.
[16]. The Latin has two Numbers,—the Singular and Plural. The Singular denotes one object, the Plural, more than one.
CASES.