Definition of overnight

overnight Adverb Throughout the night
overnight Adverb During a single night
overnight Adverb In a very short (but unspecified) amount of time
overnight Adjective Occurring between dusk and dawn.
overnight Adjective Complete before the next morning.
overnight Verb To send something for delivery the next day.
overnight Verb To stay overnight.
overnight Noun Items delivered or completed overnight.
overnight Noun An overnight stay, especially in a hotel or other lodging facility.