-tio

• -siō (in primarily third conjugation verbs with stems ending in -t-, -d-, -rg-, -ll-, or -rr-.)
• -ciō (Medieval Latin)

Either from Proto-Italic *-tjō, an n-stem extension of Proto-Indo-European *-tis. See also Proto-Indo-European *-h₃onh₂- or from Proto-Indo-European *-tyon with Old Armenian -ութիւն (-utʻiwn) as a cognate.

• (Classical) IPA^(key): /ti.oː/, [t̪ioː]
• (modern Italianate Ecclesiastical) IPA^(key): /t͡si.o/, [t̪͡s̪io] (stressed on the antepenult)

-tiō f (genitive -tiōnis); third declension

1. -tion, -ation, -ing; suffixed to a verb (usually a participle form) to form a noun relating to some action or the result of an action.

   dictātiō (“a dictating, dictation”), from dictātum, supine of dictō (“I dictate”)

   quadripartītiō (“a division into four parts”), from quadripartītum, supine of quadripartiō (“I divide in four parts”)

The suffix is occasionally added to other parts of speech, or appears in situations where no related verb apparently exists; more at -ātiō.

gradātiō (“making of a staircase or steps”), from gradus (“step, pace”).

Third-declension noun.

• -tūra, -tus

• -ātiō
• -itiō
• -ītiō

• Haudry, Jean (1981) L'indo-européen, pages 55-56
• Sihler, Andrew L. (1995) New Comparative Grammar of Greek and Latin, Oxford, New York: Oxford University Press, →ISBN