Editing Latin declension (section)

==== {{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
|}
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