'arsenyl' originates from New Latin/modern chemical formation, specifically built from the element name 'arsen-' (from Latin 'arsenicum', from Greek 'arsenikon') and the chemical suffix '-yl' (from French 'yle', used in organic nomenclature), where 'arsen-' referred to arsenic and '-yl' signified an organic radical or substituent.

'arsenyl' was coined in 19th-century chemical nomenclature by combining the established root for arsenic (from Greek 'arsenikon' via Latin 'arsenicum') with the suffix '-yl' adopted in organic chemistry (from French/German usage) to name radicals and substituents, yielding the modern term 'arsenyl'.

Initially related words referred to the element arsenic or its compounds; over time the compound form 'arsenyl' came to refer specifically to an arsenic-containing radical or substituent in organic and organometallic chemistry.