'arsenolite' originates from the element name 'arsenic' combined with Greek 'lithos' meaning 'stone' (via the mineral-naming suffix '-lite').

'arsenic' itself comes into English via Medieval Latin 'arsenicum' from Greek 'arsenikon'; the mineral name was formed in Modern English as 'arsenolite' by combining 'arsenic' + '-lite' (from Greek 'lithos').

Initially it broadly denoted a 'stone containing arsenic' or an arsenic-bearing mineral; over time it came to denote specifically the mineral arsenic trioxide (As2O3).