Mirthlessness, a word mostly used to describe the state of lacking amusement or the inability to feel joy, can be substituted with a number of synonyms. These could include dreariness, somberness, melancholy, or even desolation. People who are feeling mirthless may also be described as being gloomy, downcast, sad, or joyless. Similarly, the word could also be replaced with woefulness, unhappiness, or sorrowfulness. While there are many synonyms that could be used for mirthlessness, it is important to understand the context in which the replacement word is being used to ensure that it accurately conveys the intended meaning.