Self-assurance (noun)

The state of being certain or confident in oneself and one's abilities.

Origin:

Combination of self and assurance, meaning the state of being certain or confident in oneself.

Examples:

1. He spoke with self-assurance about his ability to complete the project.
2. She exuded self-assurance as she walked into the room.
3. He lacks self-assurance and often second-guesses himself.
4. The self-assurance she gained from her success helped her in her next venture.
5. The self-assurance he gained from his experiences helped him in his career.