Boredom research is booming. Nonetheless, a comprehensive understanding of boredom in relation to other negative emotions is lacking. This ambiguity impedes accurate interpretation of boredom’s causes and consequences. To gain more insights into boredom, we examined in detail how it differs from a range of other negative experiences, namely sadness, anger, frustration, fear, disgust, depression, guilt, shame, regret, and disappointment. Our research indicates that the appraisals associated with boredom distinguish it clearly from other negative emotions; conceptually (Study 1), in terms of state experiences (Study 2), and in terms of individual differences in these experiences (Study 3). Our findings suggest that boredom is mild in negative valence, low in arousal, is associated with low perceived challenge and low perceived meaningfulness, and has low relevance to moral judgment and behavior. Boredom also involves low attention given to situations and tasks, and the lack of perceived meaningfulness and attention associated with boredom emerged as particularly distinctive characteristics. The findings underscore the importance of carefully discriminating boredom from other emotions in experimental induction, psychometric assessment, and conceptual discussion.