The Collaborative International Dictionary of English v.0.48:

Astronomy \As*tron"o*my\, n. [OE. astronomie, F. astronomie, L.
   astronomia, fr. Gr. ?, fr. ? astronomer; 'asth`r star + ? to
   distribute, regulate. See Star, and Nomad.]
   1. Astrology. [Obs.]
      [1913 Webster]

            Not from the stars do I my judgment pluck;
            And yet methinks I have astronomy.    --Shak.
      [1913 Webster]

   2. The science which treats of the celestial bodies, of their
      magnitudes, motions, distances, periods of revolution,
      eclipses, constitution, physical condition, and of the
      causes of their various phenomena.
      [1913 Webster]

   3. A treatise on, or text-book of, the science.
      [1913 Webster]

   Physical astronomy. See under Physical.
      [1913 Webster]

WordNet (r) 3.0 (2006):

astronomy
    n 1: the branch of physics that studies celestial bodies and the
         universe as a whole [syn: astronomy, uranology]

Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "astronomy":
   astrogeology, astrognosy, astrography, astrolithology,
   astrophotography, astrophysics, celestial mechanics,
   gravitational astronomy, meteoritics, radar astronomy,
   radio astronomy, solar physics, spectrography, spectroscopy,
   stargazing, stellar photometry, uranography, uranology,
   uranometry



Easton's 1897 Bible Dictionary:

Astronomy
   The Hebrews were devout students of the wonders of the starry
   firmanent (Amos 5:8; Ps. 19). In the Book of Job, which is the
   oldest book of the Bible in all probability, the constellations
   are distinguished and named. Mention is made of the "morning
   star" (Rev. 2:28; comp. Isa. 14:12), the "seven stars" and
   "Pleiades," "Orion," "Arcturus," the "Great Bear" (Amos 5:8; Job
   9:9; 38:31), "the crooked serpent," Draco (Job 26:13), the
   Dioscuri, or Gemini, "Castor and Pollux" (Acts 28:11). The stars
   were called "the host of heaven" (Isa. 40:26; Jer. 33:22).

     The oldest divisions of time were mainly based on the
   observation of the movements of the heavenly bodies, the
   "ordinances of heaven" (Gen. 1:14-18; Job 38:33; Jer. 31:35;
   33:25). Such observations led to the division of the year into
   months and the mapping out of the appearances of the stars into
   twelve portions, which received from the Greeks the name of the
   "zodiac." The word "Mazzaroth" (Job 38:32) means, as the margin
   notes, "the twelve signs" of the zodiac. Astronomical
   observations were also necessary among the Jews in order to the
   fixing of the proper time for sacred ceremonies, the "new
   moons," the "passover," etc. Many allusions are found to the
   display of God's wisdom and power as seen in the starry heavens
   (Ps. 8; 19:1-6; Isa. 51:6, etc.)