'arsenoxide' originates from Modern English, specifically formed from the combining element 'arsen-' (from 'arsenic') and 'oxide', where 'arsen-' referred to 'arsenic' and 'oxide' referred to a compound of oxygen.

'arsen-' in 'arsenoxide' ultimately comes from Greek 'arsenikon' via Medieval Latin 'arsenicum' (meaning the arsenic mineral), and 'oxide' comes from Greek 'oxys' (acid/sharp) + the chemical suffix '-ide' via Modern Latin and French, which together produced the modern chemical-forming element 'oxide'.

Initially the component parts referred simply to the mineral or element 'arsenic' and an oxygen-containing compound; over time they have been combined in modern chemical nomenclature to mean 'an oxide of arsenic', applied to specific stoichiometric compounds such as As2O3 and As2O5.