upstart
🇺🇸
/ˈʌpstɑːrt/
🇬🇧
/ˈʌpstɑːt/
A person who has recently gained a position of importance and acts arrogantly.
The upstart CEO thought he knew everything and didn't listen to the experienced employees.
新しい社長は自分が何でも知っていると思い、経験豊富な社員の意見を聞かなかった。