Where does “ratoner” come from?

ratoner (Catalan) comes from Catalan -er, from Latin -ārius, from Proto-Italic *-āzios — Forms relational adjectives to nouns (and rarely numerals).

Ancestry of “ratoner”, step by step

StepLanguageWordMeaning
1Catalan-erUsed to form nouns meaning the location or object...
2Latin-āriuser
3Proto-Italic*-āziosForms relational adjectives to nouns (and rarely numerals)
Every word from Proto-Italic *-āzios →Every word from Latin -ārius →Every word from Catalan -er →