From Proto-Italic *-jōs, from Proto-Indo-European *-yōs, for original **-yoss, i.e. the neuter s-stem *-yos with masculine nominative *-s. The ō from the nominative case was made common to all cases. Afterwards nom.sg. -iōr > -ior, by Latin sound laws. Thus paradoxically, as in the r-stems (soror, -tor, -or), in the resulting paradigm the one form with a short stem vowel is the only form whose stem was etymologically long.
- forms adjectives’ comparative degrees
- This suffix is usually appended to the oblique stem of the adjective’s absolute degree.
Third declension, comparative variant
|Case / Gender||Masc./Fem.||Neuter||Masc./Fem.||Neuter|
- -issimus (suffix forming adjectives’ superlative degrees)
- ^ Andrew L. Sihler (1995) New Comparative Grammar of Greek and Latin, New York, Oxford, Oxford University Press
- “-ior” on page 964/3 of the Oxford Latin Dictionary (1st ed., 1968–82)