Underachiever is a term used to describe a person who fails to meet their own or others' expectations regarding their performance, effort, or success. Some synonyms for underachiever are: underperformer, low achiever, non-achiever, slacker, laggard, failure, underdog, weakling, and the like. These terms may carry negative connotations and can be perceived as derogatory. However, it's vital to note that individuals who are deemed underachievers may be struggling with various challenges, such as learning disabilities, mental health issues, lack of motivation, or minimal resources to excel. Therefore, it is essential to approach such situations with empathy, patience, and support.