From Wiktionary, the free dictionary
Jump to navigation Jump to search
See also: ius, Ius, and IUs



Etymology 1[edit]

From Old Latin -ios, from Proto-Italic *-jos, from Proto-Indo-European *-yós.


-ius (feminine -ia, neuter -ium); first/second-declension suffix

  1. forming adjectives from nouns
  2. (New Latin) suffix for Latinizing surnames
Usage notes[edit]

The suffix -ius is added to a noun to form an adjective indicating "made of" or "belonging to" that noun.

pater (father) + ‎-ius → ‎patrius (paternal)
rēx (king, ruler) + ‎-ius → ‎rēgius (kingly, royal)
uxor (wife) + ‎-ius → ‎uxōrius (uxorious)
papȳrus (papyrus) + ‎-ius → ‎papȳrius (made of papyrus)

In taxonomics[1], 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.

French Descartes + ‎-ius → ‎Cartesius
German Leibniz + ‎-ius → ‎Leibnitius
German Schmalz + ‎-ius → ‎Smalcius
English Shakespeare + ‎-ius → ‎Shakespeārius

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
Derived terms[edit]


  1. ^ Etymology: The Latinization of Modern Surnames for Species Names (July 29th), 29.07.2014, https://iam-discite.tumblr.com/post/93215833830/etymology-the-latinization-of-modern-surnames-for

Etymology 2[edit]

See -ior (suffix forming adjectives’ comparative degrees).



  1. nominative/accusative/vocative neuter singular of -ior

Etymology 3[edit]

See (suffix forming adverbs).



  1. comparative degree of

Etymology 4[edit]

From Proto-Italic *-osjos, itself from Proto-Indo-European *-ósyo (genitive case suffix) secondarily marked with the genitive *-s.



  1. the regular genitive singular suffix for most pronouns
    quī, cuius
    hic, huius
    ūnus, ūnī̆us
    alter, alterī̆us (alongside alterī, alterae)
Usage notes[edit]

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.