goodnight
interjectionUK /ˌɡʊdˈnaɪt/
US /ˌɡʊdˈnaɪt/
A kind thing you say to someone when you go to bed or when they go to bed.
Mom kissed me and said, "Goodnight, sleep well."
OTHER MEANINGS
2. A farewell said at the end of the day when people part to sleep.
After the party, everyone hugged and said goodnight.
3. Used as a noun to mean a bedtime farewell or a goodnight kiss.
She gave her little brother a quick goodnight before turning off the light.
4. A word used to end a phone call or visit late in the evening.
He whispered goodnight into the phone and hung up.