A rash, thoughtless action or conduct — acting impulsively and recklessly (four-character idiom), often used critically.
彼は感情に任せて軽挙妄動に出たが、後で後悔した。
He acted rashly in the heat of the moment and later regretted it.
組織としては、軽挙妄動を避けて慎重に決定を下す必要がある。
As an organization, it's necessary to avoid rash actions and make decisions carefully.
軽挙妄動はしばしば大きな問題を招く。
Rash and reckless behavior often leads to big problems.