Entry 5 senses · 3 variants Webster, 1913 Overnight /ōv'-ẽrn-īt'/ · O·ver·night · IPA /əʊvə(ɹ)ˈnaɪt/ n. adv. a. 01 n. The fore part of the night last past; the previous evening. 1. The fore part of the night last past; the previous evening.[R.] 02 adv. In the fore part of the night last past; in the evening before. 1. In the fore part of the night last past; in the evening before. 2. Throughout the night; as, the candle will not last overnight. 3. During the night; hence, in a short period of time; as, his prospects of winning changed overnight. “I had been telling her all that happened overnight.” — Dickens. 03 a. Ocurring or accomplished during one night; as, guaranteed overnight delivery of a package. 1. Ocurring or accomplished during one night; as, guaranteed overnight delivery of a package.