atrabilarian UK /ˌætɹəbɪˈlɛəɹi.ən/US /ˌætɹəbəˈlɛɹi.ən/ adjective1 •Characterized by melancholy or glum; atrabilarious; atrabilious.We come now to what we call the earthy or atrabilarian Constitution , where the spirituous and most fluid Parts of the Blood are dissipated — 1731 formsmore atrabilarian · most atrabilarian