good night

good night  {interj.}

1. Used as a polite phrase when you leave someone at night.

"Good night!" said Bob as he left Dick's house after the party. "I'll see you in the morning."

Bill said good night to his parents and went upstairs to bed.

2. or good grief! — Used to show surprise and often some fear or anger.

Mr. Johnson's eyes opened wide when he saw the fish his little boy had caught, and said, "Good night!"