D defs.my
Entry 1 sense Webster, 1913

Siderostat

· Sid·er·o·stat · IPA
01 n. An apparatus consisting essentially of a mirror moved by clockwork so as to throw the rays of the sun or a star in a fixed direction; -- a …
  1. 1.
    An apparatus consisting essentially of a mirror moved by clockwork so as to throw the rays of the sun or a star in a fixed direction; -- a more general term for heliostat.(Astron.)