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sidereal |
3 definitions found From Webster's Revised Unabridged Dictionary (1913) [web1913]: Month \Month\, n. [OE. month, moneth, AS m[=o]n?, m[=o]na?; akin to m[=o]na moon, and to D. maand month, G. monat, OHG. m[=a]n[=o]d, Icel. m[=a]nu?r, m[=a]na?r, Goth. m[=e]n[=o]?s. [root]272. See {Moon}.] One of the twelve portions into which the year is divided; the twelfth part of a year, corresponding nearly to the length of a synodic revolution of the moon, -- whence the name In popular use a period of four weeks is often called a month. Note: In the common law, a month is a lunar month, or twenty-eight days, unless otherwise expressed. --Blackstone. In the United States the rule of the common law is generally changed, and a month is declared to mean a calendar month. --Cooley's Blackstone. {A month mind}. a A strong or abnormal desire. [Obs.] --Shak. b A celebration made in remembrance of a deceased person a month after death. --Strype. {Calendar months}, the months as adjusted in the common or Gregorian calendar; April, June, September, and November, containing 30 days, and the rest 31, except February, which in common years, has 28, and in leap years 29. {Lunar month}, the period of one revolution of the moon, particularly a synodical revolution; but several kinds are distinguished, as the {synodical month}, or period from one new moon to the next in mean length 29 d. 12 h. 44 m. 2.87 s.; the {nodical month}, or time of revolution from one node to the same again in length 27 d. 5 h. 5 m. 36 s.; the {sidereal}, or time of revolution from a star to the same again equal to 27 d. 7 h. 43 m. 11.5 s.; the {anomalistic}, or time of revolution from perigee to perigee again in length 27 d. 13 h. 18 m. 37.4 s.; and the {tropical}, or time of passing from any point of the ecliptic to the same again equal to 27 d. 7 h. 43 m. 4.7 s. {Solar month}, the time in which the sun passes through one sign of the zodiac, in mean length 30 d. 10 h. 29 m. 4.1 s. From Webster's Revised Unabridged Dictionary (1913) [web1913]: Sidereal \Si*de"re*al\, a. [L. sidereus, from sidus, sideris a constellation, a star. Cf {Sideral}, {Consider}, {Desire}.] 1. Relating to the stars; starry; astral; as sidereal astronomy. 2. (Astron.) Measuring by the apparent motion of the stars; designated, marked out or accompanied, by a return to the same position in respect to the stars; as the sidereal revolution of a planet; a sidereal day {Sidereal clock}, {day}, {month}, {year}. See under {Clock}, {Day}, etc {Sideral time}, time as reckoned by sideral days, or taking the sidereal day as the unit, the time elapsed since a transit of the vernal equinox, reckoned in parts of a sidereal day This is strictly, apparent sidereal time, mean sidereal time being reckoned from the transit, not of the true, but of the mean equinoctial point. From WordNet r 1.6 [wn]: sidereal adj 1: of or relating to the stars or constellations; "sidereal bodies"; "the sidereal system" 2: (of divisions of time) determined by daily motion of the stars; "sidereal time" [ant: {civil}]
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