The Collaborative International Dictionary of English v.0.48:

Sideral \Sid"er*al\, a. [L. sideralis. See Sidereal.]
   1. Relating to the stars.
      [1913 Webster]

   2. (Astrol.) Affecting unfavorably by the supposed influence
      of the stars; baleful. "Sideral blast." --Milton.
      [1913 Webster]