Sidereal

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}]
    

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]
    

Month \Month\ (m[u^]nth), n. [OE. month, moneth, AS.
   m[=o]n[eth], m[=o]na[eth]; akin to m[=o]na moon, and to D.
   maand month, G. monat, OHG. m[=a]n[=o]d, Icel. m[=a]nu[eth]r,
   m[=a]na[eth]r, Goth. m[=e]n[=o][thorn]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.
   [1913 Webster]

   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.
         [1913 Webster]

   {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.
      [1913 Webster]
    

48 Moby Thesaurus words for "sidereal":
      Cynthian, anagalactic, asteroidal, astral, astrologic,
      astrologistic, astrologous, astronomic, astrophysical, celestial,
      circumplanetary, cislunar, empyreal, empyrean, equinoctial,
      extragalactic, galactic, heavenly, heliacal, intercosmic,
      interplanetary, intersidereal, interstellar, lunar, lunary, lunate,
      lunular, lunulate, meteoric, meteoritic, nebular, nebulose,
      nebulous, planetal, planetarian, planetary, planetesimal,
      semilunar, solar, sphery, star-spangled, star-studded, starry,
      stellar, stellary, terrestrial, uranic, zodiacal