The Collaborative International Dictionary of English v.0.48:

Ursa \Ur"sa\, n. [L. ursa a she-bear, also, a constellation,
   fem. of ursus a bear. Cf. Arctic.] (Astron.)
   Either one of the Bears. See the Phrases below.
   [1913 Webster]

   Ursa Major [L.], the Great Bear, one of the most
      conspicuous of the northern constellations. It is situated
      near the pole, and contains the stars which form the
      Dipper, or Charles's Wain, two of which are the Pointers,
      or stars which point towards the North Star.

   Ursa Minor [L.], the Little Bear, the constellation nearest
      the north pole. It contains the north star, or polestar,
      which is situated in the extremity of the tail.
      [1913 Webster]

U.S. Gazetteer (1990):

Ursa, IL (village, FIPS 77044)
  Location: 40.07461 N, 91.37063 W
  Population (1990): 506 (208 housing units)
  Area: 1.6 sq km (land), 0.0 sq km (water)
  Zip code(s): 62376