self-confidence; assurance; belief in oneself
何度も練習を重ねたことで、彼は大観衆の前でも_______を持ってスピーチを終えることができました。
By practicing many times, he was able to finish his speech with confidence even in front of a large audience.
commitment, promise, assurance, a definitive statement that can be held to
彼から確実な言質を取るまでは、安心できない。
I can't rest assured until I get a definite commitment from him.