atrabilarious UK /ˌætɹəbɪˈlɛəɹi.əs/US /ˌætɹəbəˈlɛɹi.əs/ adjective2 •Characterized by melancholy or gloom.This gentleman was naturally of an atrabilarious temperament, and much troubled with those phantoms of indigestion which are commonly called blue devils. — 1818 •(historical) Pertaining to black bile. formsmore atrabilarious · most atrabilarious