-arius

• (Classical) IPA^(key): /ˈaː.ri.us/, [ˈaː.ri.ʊs]

From Proto-Indo-European relational adjectival suffix *yo- (“belonging to”)

-ārius m (feminine -āria, neuter -ārium); first/second declension

1. Used to form adjectives from nouns or numerals.

   ‎camera (“vault, arch”) + ‎-ārius → ‎camerārius (“climbing, creeping”)

   ‎ordō (“line, row”) + ‎-ārius → ‎ordinārius (“ordinary, of the rank and file”)

   ‎quaternī (“four at a time, by fours”) + ‎-ārius → ‎quaternārius (“quaternary”)

First/second declension.

-ārius m (genitive -āriī); first declension

1. (masculine only) -er; Used to form nouns denoting an agent of use, such as a dealer or artisan, from other nouns.

   argentārius (“banker”), from argentum (“silver”)

   aviculārius (“bird keeper”), from avicula (“little bird”)

   rētiārius (“net fighter”), from rēte (“net”)

Second declension.