Atrabiliousness is a complex word that refers to a melancholic or gloomy state of mind. Fortunately, many synonyms exist for this word that can be used to express similar sentiments. Some of the top options include despondence, despair, dejection, gloom, and melancholy. Other possibilities include sadness, sorrow, lassitude, weariness, and ennui. Each of these words conveys a certain mood or feeling, with variations in degree or intensity. Depending on the context or desired effect, one or more of these synonyms might be an excellent alternative to using atrabiliousness.