'arsenicalism' originates from the adjective 'arsenical' (English), which itself is formed from 'arsenic' + suffix '-al', with the noun-forming suffix '-ism' added to denote a state, quality, or practice.

'arsenic' comes from Medieval Latin 'arsenicum', from Greek 'arsenikon' (ἀρσενικόν). The adjective 'arsenical' developed in English by adding '-al' to 'arsenic', and later the suffix '-ism' produced 'arsenicalism' to express the state or practice related to arsenic.

Initially terms related to 'arsenic' identified the chemical element and its compounds; over time formations like 'arsenicalism' came to denote either the presence/quality of arsenic or the practice/use (sometimes with negative connotations of poisoning).