1. (Science: physics) The twenty-fourth part of a day; sixty minutes.
3. Fixed or appointed time; conjuncture; a particular time or occasion; as, the hour of greatest peril; the man for the hour. Woman, . . . Mine hour is not yet come. (john II. 4) This is your hour, and the power of darkness. (Luke xxii. 53)
5. (Science: astronomy) hour angle, a line on which the shadow falls at a given hour; the intersection of an hour circle which the face of the dial. Hour plate, the plate of a timepiece on which the hours are marked; the dial. Sidereal hour, the twenty-fourth part of a sidereal day. Solar hour, the twenty-fourth part of a solar day. The small hours, the early hours of the morning, as one o'clock, two o'clock, etc. To keep good hours, to be regular in going to bed early.
Origin: oe. Hour, our, hore, ure, OF. Hore, ore, ure, f. Heure, L. Hora, fr. Gr, orig, a definite space of time, fixed by natural laws; hence, a season, the time of the day, an hour. See year, and cf. Horologe, horoscope.