The ability to maintain one's will or intent despite either the experience of fear, frailty, or frustration; or the occurrence of adversity, difficulty, defeat or reversal. Moral fortitude.
The ability to overcome one's fear, do or live things which one finds frightening.
The quality of being confident, not afraid or easily intimidated, but without being incautious or inconsiderate.
Courage, fortitude, or machismo.
Testicles; bollocks.