From Old Latin -ios, from Proto-Italic *-jos, from Proto-Indo-European *-yós.
-ius (feminine -ia, neuter -ium); first/second-declension suffix
The suffix -ius is added to a noun to form an adjective indicating "made of" or "belonging to" that noun.
In taxonomics, out of analogy with ancient Roman cognomina, this suffix is added to surnames ending in a consonant other than the ending -er and, sometimes, replacing a mute final -e.
First/second-declension adjective.
Number | Singular | Plural | |||||
---|---|---|---|---|---|---|---|
Case / Gender | Masculine | Feminine | Neuter | Masculine | Feminine | Neuter | |
Nominative | -ius | -ia | -ium | -iī | -iae | -ia | |
Genitive | -iī | -iae | -iī | -iōrum | -iārum | -iōrum | |
Dative | -iō | -iō | -iīs | ||||
Accusative | -ium | -iam | -ium | -iōs | -iās | -ia | |
Ablative | -iō | -iā | -iō | -iīs | |||
Vocative | -ie | -ia | -ium | -iī | -iae | -ia |
See -ior (suffix forming adjectives’ comparative degrees).
-ius
See -ō (suffix forming adverbs).
-ius
From Proto-Italic *-osjos, itself from Proto-Indo-European *-ósyo (“genitive case suffix”) secondarily marked with the genitive *-s.
-ius
Like 3d- and 4th-declension, and unlike 1st- and 2nd-declension forms, has one form for all genders. A gendered adjective option also exists for cuius.