Nonachiever is a term used to describe someone who has not achieved a desired level of success or accomplishment. However, there are several synonyms for nonachiever that can be used to describe someone who has not achieved success. These synonyms include underachiever, unsuccessful, failure, loser, flopper, dud, underdog, and ne'er-do-well. All of these terms describe someone who has not been able to achieve their goals. While some of these terms may be considered derogatory, they are useful for describing individuals who may need encouragement or additional support to reach their full potential. It is important to remember that failure is often a stepping stone to success.