overnighto‧ver‧night1 /ˌəʊvəˈnaɪt $ ˌoʊvər-/ ●●○ adverb1Dfor or during the nightPam’s staying overnight at my house.2SUDDENLYsuddenly or surprisingly quicklyHe became a millionaire overnight.happen/appear/change overnightReputations are not changed overnight. ► Do not talk about ‘an overnight’ because overnight is never a noun. It is either an adverb or an adjective.
overnighto‧ver‧night2 /ˈəʊvənaɪt $ ˈoʊvər-/ ●●○ adjective1TIME/HOW LONGhappening during the night or for the nightan overnight flight to Chicagoovernight accommodation in London2happening surprisingly quicklyThe show was an overnight success.his overnight decision to become a vegetarian
Examples from the Corpus
overnight• She gave him five minutes to pack an overnightbag under Dexter's supervision and say farewell to his family.• an overnightdeliveryservice• In 1981, it had 26 percent of the overnightmarket; by 1989, it was down to 12 percent.• After an overnightrain, the skyappearedclear and blue.• The keyovernightrate will settle at 0. 45 percent, the same as yesterday, a money market broker said.• Dealerfinancing rate for overnightsale and repurchase of Treasury securities.• They take eighteen hours all told, including the overnightsoaking.From Longman Business Dictionaryovernighto‧ver‧night1 /ˌəʊvəˈnaɪt◂ˌoʊvər-/ adjective [only before a noun]1done in one nightMuch of what is shipped via overnight express delivery is not really needed the next day.2continuing for all or most of the nightan overnight flight3happening last nightLondon stocks ended higher, fueled by overnight gains on Wall Street.4overnight money is lent for one night and must be paid back the next dayCredit was tightened and the cost of overnight money touched 10%.overnight commercial paper —overnight adverbovernightovernight2 verb [transitive] American EnglishTRANSPORTto send something overnightWe were told on Thursday that our check would be overnighted to us on Friday.