An excuse or pretext used to hide the real reason; a stated reason to justify or avoid something.
彼は遅刻の口実に渋滞を挙げたが、本当の理由は寝坊だった。
He blamed traffic as an excuse for being late, but the real reason was oversleeping.
口実を作らずに素直に謝った方がいい。
It's better to apologize honestly than to make excuses.
会議を抜ける口実を考える必要があった。
I needed to think of a pretext to leave the meeting.