[AS.] A word originally used to indicate tne period of time during which it was light, in contrast to night or the period of darkness. This usage still exists, but a day in its civil or legal sense, is now the period between midnight and the succeeding midnight, or 24 hours. The siderial day, which is based on a seeming revolution of the stars, instead of the sun, is shorter, being 23 hrs. 56 min. 49 sec. Astronomers reckon the day as beginning at noon, and count the hours from 1 to 24.