overnight

the word 'overnight' is a transparent compound formed from two native english elements. the prefix 'over', with its sense of passage across a space or time, is combined with the noun 'night', referring to the dark period of a full day. this literal combination, meaning "through the course of the night," dates to old english. over time, the temporal sense extended metaphorically to describe events that happen very suddenly or completely, as if they were accomplished in the span of a single night, giving rise to its common figurative meaning denoting rapid change.

Structure: over (across, beyond) + night (the period of darkness) - over: from old english 'ofer', meaning "above, across, beyond". functions as a prefix indicating passage or duration across a span. - night: from old english 'niht', meaning "the period of darkness between sunset and sunrise". functions as the core noun root specifying the time period.