Underperforming is a term that can be used to describe someone or something that is not meeting expectations. Some synonyms for underperforming include inadequate, subpar, deficient, inferior, below average, lackluster, and unsatisfactory. These terms can be used to describe various situations where performance falls short, such as in academics, work, sports, or personal goals. It is important to note that underperforming should not always be seen as a negative trait, as it can serve as an opportunity for growth and improvement. Synonyms like underperforming should be used constructively and with the intention of helping someone or something reach their full potential.