self-assured
US /ˌself əˈʃʊrd/
UK /ˌself əˈʃʊrd/

1.
autoconfiante, seguro de si
confident in one's own abilities or character
:
•
She walked into the room with a self-assured smile.
Ela entrou na sala com um sorriso autoconfiante.
•
His calm and self-assured demeanor impressed everyone.
Sua postura calma e autoconfiante impressionou a todos.