A day (symbol d) is a unit of time equivalent to approximately 24 hours. ... The word 'day' can also refer to the (roughly) half of the day that is not night, also ...
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day n. The period of light between dawn and nightfall; the interval from sunrise to sunset. The 24-hour period during which the earth completes one
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D-day ( ) n. The unnamed day on which an operation or offensive is to be launched. The day on which the Allied forces invaded France during World War
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