Editing Latin declension (section)

=== {{anchor|d2}}{{anchor|Second declension}} Second declension (''o'' stems) ===
The second declension is a large group of nouns consisting of mostly masculine nouns like {{wikt-lang|la|equus|equus, equī}} ('horse') and {{wikt-lang|la|puer|puer, puerī}} ('boy') and neuter nouns like {{wikt-lang|la|castellum|castellum, castellī}} ('fort'). There are several small groups of feminine exceptions, including names of [[gemstone]]s, plants, trees, and some towns and cities.

In the nominative singular, most masculine nouns consist of the [[Stem (linguistics)|stem]] and the [[Suffix#Inflectional suffixes|ending]] ''-us'', although some end in ''-er'', which is not necessarily attached to the complete stem. Neuter nouns generally have a nominative singular consisting of the stem and the ending ''-um''. However, every second-declension noun has the ending ''-ī'' attached as a suffix to the root of the noun in the genitive singular form. The predominant letter in the ending forms of this declension is ''o''.

{| class="wikitable"
|+ Second declension paradigm
|-
! rowspan="2" |
! colspan="2" | Singular
! colspan="2" | Plural
|-
! Masculine || Neuter
! Masculine || Neuter
|-
! Nominative
| -us  ||   rowspan="3"| -um || rowspan="2"| -ī ||rowspan="3"| -a
|-
! Vocative
| -e
|-
! Accusative
| -um || -ōs
|-
! Genitive
| colspan="2"|-ī ||colspan="2"| -ōrum
|-
! Dative, Ablative
| colspan="2" | -ō  || colspan="2" | -īs
|-
! Locative
| colspan="2"| ''Gen.'' || colspan="2"| ''Dat.''
|}
{| class="wikitable"
|+ Masculine
! rowspan="2" |
! colspan="2" | {{wikt-lang|la|dominus|dominus, dominī}}<br />master {{abbr|m.|masculine}}
|-
! Singular
! Plural
|-
! Nominative
| dominus || rowspan="2" | dominī
|-
! Vocative
| domine
|-
! Accusative
| dominum || dominōs
|-
! Genitive
| dominī || dominōrum
|-
! Dative, Ablative
| dominō || dominīs
|}

{| class="wikitable"
|+ Neuter
! rowspan="2" |
! colspan="2" | {{wikt-lang|la|bellum|bellum, bellī}}<br />war {{abbr|n.|neuter}}
|-
! Singular
! Plural
|-
! Nominative, Vocative, Accusative
| bellum || bella
|-
! Genitive
| rowspan="2" | bellī || bellōrum
|-
! Locative
| rowspan="2" | bellīs
|-
! Dative, Ablative
| bellō
|}

The locative endings for the second declension are ''-ī'' (singular) and ''-īs'' (plural); {{wikt-lang|la|Corinthus|Corinthī}} "at Corinth", {{wikt-lang|la|Mediolanum|Mediolānī}} "at Milan", and {{wikt-lang|la|Philippi|Philippīs}} "at Philippi".<ref>Allen and Greenough. §49 a.</ref>

==== {{anchor|d2r}} Second-declension ''-ius'' and ''-ium'' nouns ====
Nouns ending in ''-ius'' and ''-ium'' have a genitive singular in ''-ī'' in earlier Latin, which was regularized to ''-iī'' in the later language. Masculine nouns in ''-ius'' have a vocative singular in ''-ī'' at all stages. These forms in ''-ī'' are stressed on the same syllable as the nominative singular, sometimes in violation of the usual Latin stress rule. For example, the genitive and vocative singular ''Vergilī'' (from {{wikt-lang|la|Vergilius}}) is pronounced ''Vergílī'', with stress on the penult, even though it is short.<ref>Gildersleeve & Lodge §15, Allen & Greenough §12, §49c</ref> In Old Latin, however, the vocative was declined regularly, using ''-ie'' instead, e.g. ''fīlie'' "[O] son", archaic vocative of {{Lang|la|fīlius}}.

There is no contraction of ''-iī(s)'' in plural forms and in the locative.

{| class="wikitable"
! rowspan="2" |
! colspan="2" | {{wikt-lang|la|filius|fīlius, filiī}}<br />son {{abbr|m.|masculine}}
! colspan="2" | {{wikt-lang|la|auxilium|auxilium, auxiliī}}<br />aid, help {{abbr|n.|neuter}}
|-
! Singular
! Plural
! Singular
! Plural
|-
! Nominative
| {{Lang|la|fīlius}} || rowspan="2" | {{Lang|la|fīliī}}  || rowspan="3" | {{Lang|la|auxilium}}  || rowspan="3" | {{Lang|la|auxilia}}
|-
! Vocative
| {{Lang|la|fīlī}}
|-
! Accusative
| {{Lang|la|fīlium}} || {{Lang|la|fīliōs}}
|-
! Genitive
| {{Lang|la|fīliī}}  || {{Lang|la|fīliōrum}}  || {{Lang|la|auxiliī}}  || {{Lang|la|auxiliōrum}}
|-
! Dative, Ablative
| {{Lang|la|fīliō}}  || {{Lang|la|fīliīs}}  || {{Lang|la|auxiliō}}  || {{Lang|la|auxiliīs}}
|}

In the older language, nouns ending with ''-vus'', ''-quus'' and ''-vum'' take ''o'' rather than ''u'' in the nominative and accusative singular. For example, {{wikt-lang|la|servis|servus, servī}} ('slave') could be ''servos'', accusative ''servom''.

==== {{anchor|d2r}} Second-declension ''-r'' nouns ====
Some masculine nouns of the second declension end in ''-er'' or ''-ir'' in the nominative singular. The declension of these nouns is identical to that of the regular second declension, except for the lack of suffix in the nominative and vocative singular.

Some (but not all) nouns in ''-er'' drop the ''e'' in the genitive and other cases. For example, {{wikt-lang|la|socer|socer, socerī}} ('father-in-law') keeps its ''e''. However, the noun {{wikt-lang|la|magister|magister, magistrī}} ('(school)master') drops its ''e'' in the genitive singular.

For declension tables of second-declension nouns, see the [[Wiktionary:Appendix:Latin second declension|corresponding Wiktionary appendix]].

{| class="wikitable"
! rowspan="2" |
! colspan="2" | {{wikt-lang|la|puer|puer, puerī}}<br />boy {{abbr|m.|masculine}}
! colspan="2" | {{wikt-lang|la|ager|ager, agrī}}<br />field {{abbr|m.|masculine}}
! colspan="2" | {{wikt-lang|la|vir|vir, virī}}<br />man {{abbr|m.|masculine}}
|-
! Singular
! Plural
! Singular
! Plural
! Singular
! Plural
|-
! Nominative,Vocative
| puer || puerī || ager || agrī || vir || virī
|-
! Accusative
| puerum || puerōs || agrum || agrōs || virum || virōs
|-
! Genitive
| puerī || puerōrum || agrī || agrōrum || virī || virōrum<br />(virum)
|-
! Dative, Ablative
| puerō || puerīs || agrō || agrīs || virō || virīs
|}

The vocative ''puere'' is found but only in [[Plautus]].<ref>[https://www.perseus.tufts.edu/hopper/searchresults?target=la&all_words=puere Perseus database.]</ref> The genitive plural ''virum'' is found in poetry.<ref>Gildersleeve & Lodge, ''Latin Grammar'' 3rd ed., p. 17.</ref>

==== {{anchor|d2g}} Second-declension Greek nouns ====

{{Main|Declension of Greek nouns in Latin}}

The second declension contains two types of masculine Greek nouns and one form of neuter Greek noun. These nouns are irregular only in the singular, as are their first-declension counterparts. Greek nouns in the second declension are derived from the [[Ancient Greek nouns#Second declension|Omicron declension]].

Some Greek nouns may also be declined as normal Latin nouns. For example, {{wikt-lang|la|theātron}} can appear as ''theātrum''.

==== {{anchor|d2i}} Irregular forms ====

===== Deus =====
The inflection of {{wikt-lang|la|deus|deus, deī}} ('god') is irregular. The vocative singular of ''deus'' is not attested in Classical Latin. In [[Ecclesiastical Latin]] the vocative of ''Deus'' ('God') is ''Deus''.

In poetry, ''-um'' may substitute ''-ōrum'' as the genitive plural ending.

{| class="wikitable"
! rowspan="2" |
! colspan="2" | ''deus, deī''<br />god {{abbr|m.|masculine}}
|-
! Singular
! Plural
|-
! Nominative, Vocative
|deus ||deī<br />diī<br />dī
|-
! Accusative
| deum || deōs
|-
! Genitive
| deī || deōrum<br />deum
|-
! Dative, Ablative
| deō || deīs<br />diīs<br />dīs
|}

===== Virus =====
Three words, although second declension neuter, end in ''-us''. These are {{lang|la|vulgus}} "common people, crowd", {{lang|la|vīrus}} "slime, poison", and (borrowed from Greek) {{lang|la|pontus}} "sea".<ref>Ernout (1953), p. 34.</ref>

The word {{lang|la|vīrus}} means "1. slimy liquid, slime; 2. poison, venom", denoting the venom of a snake. This Latin word is probably related to the [[Greek language|Greek]] {{wikt-lang|grc|ῑ̓ός}} (''ios'') meaning "venom" or "rust" and the [[Sanskrit]] word {{wikt-lang|sa|विष}} ''{{Transliteration|sa|viṣa}}'' meaning "toxic, poison".<ref>Chambers' Etymological Dictionary Enlarged Edition 1931.</ref>

Since {{lang|la|vīrus}} in antiquity denoted something uncountable, it was a [[mass noun]]. Mass nouns pluralize only under special circumstances, hence the non-existence of plural forms in the texts.<ref>June 1999 issue of ASM News by the American Society for Microbiology</ref>

In [[Neo-Latin]], a plural form is necessary in order to express the modern concept of 'viruses', which leads to the following declension:<ref>[https://web.archive.org/web/20170728043240/interrete.de/latein/nuntiifinarch1.html Nuntii Latini: Finnish Broadcasting Company (Radiophonia Finnica Generalis). Archiv I. 19.5.2000 – 6.12.2002]: "NOVUM VIRUS COMPUTATORIUM<br />Novum viri computatorii genus nomine Code Red in praesenti in Interreti grassatur, ut nuntiavit institutum SANS, cuius est securitati retis informatici providere. Code Red II, quod per cursum electronicum diffunditur, priore viro acerbius est et, postquam in servitoria penetravit, in systema lacunam facit. Ita fieri potest, ut alia vira eaque etiam periculosiora in machinas computatorias irrepant. Iam vermis Code Red I molestissimus fuit, cum biduo in trecenta milia computatrorum in omni orbe terrarum invasit."</ref><ref>[https://de.pons.com/%C3%BCbersetzung?l=dela&q=virus Pons: ''virus'']</ref><ref>William T. Stearn: ''Botanical Latin. History, Grammar, Syntax, Terminology and Vocabulary.'' David & Charles, third edition, 1983. Quote: "Virus: virus (s.n. II), ''gen. sing.'' viri, ''nom. pl.'' vira, ''gen. pl.'' vīrorum (to be distinguished from ''virorum'', of men)."</ref>

{| class="wikitable"
! rowspan="2" |
! colspan="2" | ''{{wikt-lang|la|virus|vīrus, vīrī}}''<br />poison, venom, virus {{abbr|n.|neuter}}
|-
! Singular
! Plural
|-
! Nominative, Vocative, Accusative
| vīrus || vīra
|-
! Genitive
| vīrī{{efn-lr|antique, [[Proto-Indo-European nominals#Heteroclitic stems|heteroclitic]]: vīrus{{citation needed|date=November 2021}}}} || vīrōrum
|-
! Dative, Ablative
| vīrō || vīrīs
|}
{{notelist-lr}}