Definition
To have a strong sense of confidence in one's abilities or judgment, sometimes to an excessive degree.
自信满满；过度自信
She has become very sure of herself since she started performing on stage.
自从她开始在舞台上表演后，她变得非常自信。
He is always very sure of himself in his choices, never doubting his decisions.
他总是对自己的选择非常自信，从不怀疑自己的决定。
She's so sure of herself that she sometimes comes across as arrogant.
她如此自信，以至于有时给人一种傲慢的感觉。