1. to lack confidence in one's own abilities, decisions, or worth; to question one's own capabilities or judgment
After the failed presentation, she began to doubt herself about her professional skills.
Após a apresentação fracassada, ela começou a duvidar de si mesma sobre suas habilidades profissionais.
2. to experience uncertainty or lack of faith in one's own choices or actions
He doubted himself when making the important life decision.
Ele duvidou de si mesmo ao tomar a importante decisão de vida.