-iō¹

Meaning

1. morphemeUsed to form fourth conjugation verbs.

Origins

Ultimately from Proto-Indo-European *-yéti (denominative suffix). The question of how it came to be differentiated from third-conjugation -iō, -ere still debated. Vine 2012 derives denominatives such as serviō from *serw-e-yé/ó- (with the thematic vowel *-e- before the suffix), proposing that unaccented Proto-Indo-European *-e- came to be assimilated in Italic to an immediately following *-y-. Alternative explanations include an Italic version of Sievers's law (that is, a prosodically conditioned development of postconsonantal *-y-* to *-iy- in certain contexts) or combination of the suffix with stems ending in *-i-. Some verbs may be derived from backformation from adjectives ending in -ītus, such as igniō, whose finite forms are attested later than ignītus (“fiery, glowing”).

Meaning

1. morphemeattached to noun stems, forms nouns referring to a related profession
   libellus (“booklet”) + -iō → libelliō m (“notary; bookdealer”)
   lūdus (“performance, stage play”) + -iō → lūdiō m (“stage performer”)
2. morphemerareattached to verb stems, forms agent nouns
   lēx (“law”) + rumpō (“break”) + -iō → lēgirupiō m (“law-breaker”)
3. morphemealso forms names, especially cognomina.
   glaber (“smooth, hairless”) + -iō → Glabriō (“a Roman cognomen”)
   ursus (“bear”) + -iō → Ursiō (“a Roman cognomen”)
4. morphemeattached to noun stems, forms a diminutive or similar derived noun
   caballus (“horse”) + -iō → caballiō m (“pony”)
   porcellus (“little pig”) + -iō → porcelliō m (“woodlouse”)
5. morphemeSuffixed to noun or adjective stems, forms certain nouns designating things; often described as a kind of diminutive.

Origins

Proto-Indo-European *-ōder. Proto-Indo-European *-Hōder.? Latin -ō Latin -io Extension of -ō (possibly by rebracketing).

Meaning

1. morphemeUsed to form abstract nouns from verbs.
   obsideō (“to remain; to besiege”, verb) + -io → obsidiō f (“siege, blockade”)
   opīnor (“to suppose, deem, opine”, verb) + -io → opīniō f (“opinion, conjecture; reputation; report”)

Origins

Suffix -ō on i-stems.

Meaning

1. morphemeUsed to form factitive verbs from adjectives.

Origins

From -i-ō. Ultimately from Proto-Indo-European *-yeti.

Meaning

1. morphemeending of some third conjugation verbs

Origins

Disputed. Perhaps from Proto-Italic *-jō, from Proto-Indo-European *-yéti (first person singular: *-yóh₂). Linguists such as Michael Weiss prefer to connect this class with the PIE thematic ye-suffix, explaining the split between third conjugation iō-verbs and the fourth conjugation as the result of a series of phonological developments. De Vaan and Schrijver, however, connect the suffix with the athematic ablauting i-present type *-éyti.