Happening during the night or instantly without delay
Examples:
I stayed at his house overnight.She became famous overnight after her video went viral.
Synonyms:
Antonyms:
Over night
/ˌoʊvəˈnaɪt/
Happening suddenly or in a very short time, usually referring to an event or change that occurs from one evening until the next morning
Examples:
Synonyms:
Antonyms:
Ways to tell them apart:
Overnight is a single word combining over and night.
Use overnight when describing something happening throughout the night or over an entire night.
Over night, as two separate words, is rarely used unless specifically discussing the concept of over relative to the night, like a question about the night sky.