This is the 8007th most frequent Japanese word.
失せ
"失せ" (use) means "to disappear" or "to vanish."
In this sentence, the word '失せ' refers to something disappearing or vanishing suddenly, indicating the cessation of a feeling or presence.
彼の熱意は突然失せた。
His enthusiasm suddenly vanished.
Here, '失せ' means to go missing or be lost, highlighting the absence of something once expected to be present.
そのプレゼントを開けて、中身が失せていたら困る。
Opening the present and finding its contents gone would be troubling.
In this usage, '失せ' is used colloquially to demand someone to leave or disappear, carrying a strong imperative tone.