day

The Sailor's Word-Book

The astronomical day is reckoned from noon to noon, continuously through the twenty-four hours, like the other days. It commences at noon, twelve hours after the civil day, which itself begins twelve hours after the nautical day, so that the noon of the civil day, the beginning of the astronomical day, and the end of the nautical day, occur at the same moment. (See the words solar day and sidereal day.)

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