LATIN DICTIONARYLexicon Latīnum
suffix · neutersecond declension

-ōrium

-ōrium n (genitive -ōriī)
Classical[oː.ri.ũː]Ecclesiastical[o.ri.um]

Meaning

  1. Medieval Latinmorphemesuffix forming nouns, usually denoting places or objects
    ferveō /fervor (“to boil / boiling heat”) + -ōrium → fervōrium (“cauldron”)
    lavō (“to wash, to bathe”) + -ōrium → lavōrium /lavārium (“washroom, wash basin”)

Origins

Rebracketing of -tōrium; or an alteration of -ārium, perhaps also influenced in some cases by the abstract noun suffix -or (as in sūdōrium, a medieval alternative form of sūdārium, from sūdor).

Quick answers

What does -ōrium mean in Latin?
-ōrium, a suffix, means “suffix forming nouns, usually denoting places or objects”.
How do you pronounce -ōrium?
In classical Latin, [oː.ri.ũː]; in ecclesiastical (church) Latin, [o.ri.um].