1. A person who does not perform as well as expected or as well as they are capable of performing, especially in academic or professional contexts
Despite his intelligence, he was labeled an underachiever because his grades didn't reflect his abilities.
Apesar de sua inteligência, ele foi rotulado como alguém que não atingia seu potencial porque suas notas não refletiam suas capacidades.
2. Someone whose accomplishments fall short of predictions or expectations based on their potential
The coach identified him as an underachiever who needed more motivation.
O técnico o identificou como alguém que não realizava seu potencial e que precisava de mais motivação.