Secunda Dēclīnātiō

45. The Stem of nouns of the Second Declension ends in o-: as virō- (stem of vir, man), servō- (stem of servus or servos, slave), bellō- (stem of bellum, war).

a. The Nominative is formed from the stem by adding s in masculines and feminines, and m in neuters, the vowel o being weakened to u (see §§ 6. a, 46. n.²).

b. In most nouns whose stem ends in ro- the s is not added in the Nominative, but o is lost, and e intrudes before r, if not already present: as ager, stem agro-; cf. puer, stem puerō-.

Exceptions: erus, hesperus, iūniperus, mōrus, numerus, taurus, umerus, uterus, virus, and many Greek nouns.

c. The stem-vowel o has a variant form e, which is preserved in the Latin vocative singular of nouns in -us: as servē, vocative of servus, slave.

46. Nouns of the Second Declension in -us (-os) and -um (-om) are thus declined:

47. Nouns of the Second Declension in -er and -ir are thus declined:

48. Nouns ending in -us (-os), -er, -ir, are Masculine; those ending in -um (-on) are Neuter.

Exceptions: Names of countries and towns in -us (-os) are Feminine: as Aegyptus, Corinthus. Also many names of plants and gems, with the following: alvus, belly; carbasus, linen (pl. carbasa, sails, N.); colus, distaff; humus, ground; vannus, winnowing-shovel.

Many Greek nouns retain their original gender: as arctus (F.), the Polar Bear; methodus (F.), method.

a. The following in -us are Neuter; their accusative (as with all neuters) is the same as the nominative: pelagus, sea; vīrus, poison; vulgus (rarely M.), the crowd. They are not found in the plural, except pelagus, which has a rare nominative and accusative plural pelagē.

a. The Locative form of this declension ends for the singular in -ī: as humī, on the ground; Corinthī, at Corinth. For the plural, in -īs: as Philippīs, at Philippi.

b. The genitive of nouns in -ius or -ium ended, until the Augustan Age, in a single -ī: as fīlī, of a son; Pompēī, of Pompey (Pompēius); but the accent of the nominative is retained: as ingé'nī, of genius.

c. Proper names in -ius have -ī in the vocative, retaining the accent of the nominative: as Vergī'lī. So also fīlius, son; genius, divine guardian: as audī, mī fīlī, hear, my son.

Adjectives in -ius form the vocative in -ie, and some of these are occasionally used as nouns: as Lacedaemonie, O Spartan.

d. The genitive plural often has -um or (after v) -om (cf. § 6. a) instead of -ōrum, especially in the poets: as deum, superum, dīvom, of the gods; virum, of men. Also in compounds of vir, and in many words of money, measure, and weight: as Sēvirum, of the Seviri; nummum, of coins; iūgerum, of acres.

g. Deus (M.), god, is thus declined:

50. The following stems in ero-, in which e belongs to the stem, retain the e throughout and are declined like puer (§ 47):

Also, the adjective līber, free, of which līberī, children, is the plural; and compounds in -fer and -ger (stem fero-, gero-): as lūcifer, morning star; armiger, squire.

51. The following, not having e in the stem, insert it in the nominative singular and are declined like ager (§ 47):

52. Greek nouns of the Second Declension end in -os, -ōs, masculine or feminine, and in -on neuter. They are mostly proper names and are declined as follows in the Singular, the Plural — when found — being regular:

a. Many names in -ēs belonging to the third declension have also a genitive in -ī: as Thūcydidēs, Thūcydidī.

b. Several names in -er have also a nominative in -us: as Teucer or Teucrus. The name Panthūs has the vocative Panthū.

c. The genitive plural of certain titles of books takes the Greek termination -ōn: as Geōrgicōn, of the Georgics.

d. The termination -oe (for Greek -oi) is sometimes found in the nominative plural: as Adelphoe, the Adelphi (a play of Terence).

e. Greek names in -eus (like Orpheus) have forms of the second and third declensions (see § 82).