-ior

From Proto-Italic *-jōs, from Proto-Indo-European *-yōs, for original **-yoss, i.e. the 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.[1]

• (Classical) IPA^(key): /i.or/, [iɔr]
• (modern Italianate Ecclesiastical) IPA^(key): /i.or/, [ior] (stressed on the antepenult)

-ior m or f (neuter -ius); third declension

1. forms adjectives’ comparative degrees

   esculentus → esculentior

   pūtidus → pūtidior

   ulter → ulterior (not *ultrior)

• This suffix is usually appended to the oblique stem of the adjective’s absolute degree.

Third-declension comparative adjective.

• -issimus (suffix forming adjectives’ superlative degrees)

• “-ior” on page 964/3 of the Oxford Latin Dictionary (1st ed., 1968–82)

Inherited from Latin -olus.

-ior m (plural -iori, feminine -ioară, feminine plural -ioare)

1. Forms diminutives of nouns.

   ‎frate (“brother”) + ‎-ior → ‎frățior

   ‎mia (“ewe”) + ‎-ior → ‎mioară

The "i" sometimes leads to the palitalization of the previous consonant and gets subsequently deleted.

• ‎obraz (“cheek”) + ‎-ior → ‎obrăjor

• -șor