おやすみなさい (goodnight)

おやすみなさい — 'goodnight,' literally 'please rest.' The standard Japanese nighttime farewell, said before sleep or when parting late in the evening. Casual form: おやすみ (used among family, partners, and close friends). Morphologically a polite imperative (お~なさい from 休む 'to rest'), but fossilized as a fixed greeting. Distinct from さようなら ('goodbye'), which is more permanent or formal.