小胆

彼の小胆が計画の失敗を招いた。

His timidity led to the failure of the plan.

そんな小胆なことでは大きな仕事は任せられない。

If you're that faint-hearted, we can't trust you with a big job.

彼は小胆な性格で、人前に出るとすぐに緊張する。

He has a timid nature and gets nervous as soon as he's in front of people.