'atrabilarian' ultimately originates from Latin, specifically the word 'atrabilis' (from 'ater' + 'bilis'), where 'ater' meant 'black' and 'bilis' meant 'bile'.

'atrabilarian' developed via Late Latin/Medieval Latin terms related to 'atrabilis' and the adjective 'atrabilious' (meaning 'melancholic, caused by black bile'), and entered English usage as a rare adjective/noun (from 17th–18th century formations).

Initially it referred to matters relating to 'black bile' (the humoral theory cause of melancholy); over time it came to mean simply 'melancholic' or 'ill-tempered' without medical implication.