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. [1913 Webster]

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. [1913 Webster]

{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. [1913 Webster]

The Collaborative International Dictionary of English. 2000.


Look at other dictionaries:

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  • day — /day/, n. 1. the interval of light between two successive nights; the time between sunrise and sunset: Since there was no artificial illumination, all activities had to be carried on during the day. 2. the light of day; daylight: The owl sleeps… …   Universalium

  • day — [ deı ] noun *** 1. ) count one of the periods of time that a week is divided into, equal to 24 hours: We re going away for five days. The animals are kept inside for 14 hours a day. 24 hours a day (=during the whole of the day and night): The… …   Usage of the words and phrases in modern English

  • Day — (d[=a]), n. [OE. day, dai, dei, AS. d[ae]g; akin to OS., D., Dan., & Sw. dag, G. tag, Icel. dagr, Goth. dags; cf. Skr. dah (for dhagh ?) to burn. [root]69. Cf. {Dawn}.] 1. The time of light, or interval between one night and the next; the time… …   The Collaborative International Dictionary of English

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  • day — [dā] n. [ME dai < OE dæg (pl. dagas), akin to ON dagr, Goth dags, OHG tag < PGmc * dagwaz, prob. < IE base * ag̑hes, day, with d by assoc. with base * dhegwh , to burn] 1. a) the period of light between sunrise and sunset b) daylight c)… …   English World dictionary

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  • day — [n1] light part of every 24 hours astronomical day, bright, dawn to dark, daylight, daytime, diurnal course, early bright, light, light of day, mean solar day, nautical day, sidereal day, sunlight, sunrise to sunset, sunshine, working day;… …   New thesaurus

  • day — s.m.inv. ES ingl. {{wmetafile0}} giorno in cui si verifica un avvenimento o si celebra una ricorrenza; posposto a un sostantivo e preceduto da un trattino forma lessemi s.m.inv.: compleanno day, matrimonio day, Giampaolo Rossi day {{line}}… …   Dizionario italiano

  • day — O.E. dæg day, also lifetime, from P.Gmc. *dagaz (Cf. O.S., M.Du., Du. dag, O.Fris. dei, O.H.G. tag, Ger. Tag, O.N. dagr, Goth. dags), from PIE *dhegh . Not considered to be related to L. dies (see DIURNAL (Cf …   Etymology dictionary

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