'arsenite' originates from New Latin, specifically the word 'arsenites', where 'arsen-' ultimately comes from Latin 'arsenicum' (from Greek 'arsenikon') and the suffix '-ite' denotes salts or minerals in chemical/mineral names.

'arsenite' changed from Modern/ New Latin 'arsenites' used in chemical nomenclature and entered English as a term for salts of arsenous acid, evolving from Latin 'arsenicum' (and Greek 'arsenikon') into the modern English 'arsenite'.

Initially, the related terms referred more generally to minerals or compounds of arsenic; over time 'arsenite' came to mean specifically a salt or ion of arsenous acid (arsenic in oxidation state +3).