The Collaborative International Dictionary of English v.0.48:

Cinnabar \Cin"na*bar\, n. [L. cinnabaris, Gr. ?; prob. of
   Oriental origin; cf. Per. qinb[=a]r, Hind. shangarf.]
   [1913 Webster]
   1. (Min.) Red sulphide of mercury, occurring in brilliant red
      crystals, and also in red or brown amorphous masses. It is
      used in medicine.
      [1913 Webster]

   2. The artificial red sulphide of mercury used as a pigment;
      vermilion.
      [1913 Webster]

   Cinnabar Gr[ae]corum. [L. Graecorum, gen. pl., of the
      Greeks.] (Med.) Same as Dragon's blood.

   Green cinnabar, a green pigment consisting of the oxides of
      cobalt and zinc subjected to the action of fire.

   Hepatic cinnabar (Min.), an impure cinnabar of a
      liver-brown color and submetallic luster.
      [1913 Webster]

WordNet (r) 3.0 (2006):

cinnabar
    adj 1: of a vivid red to reddish-orange color [syn: vermilion,
           vermillion, cinnabar, Chinese-red]
    n 1: a heavy reddish mineral consisting of mercuric sulfide; the
         chief source of mercury
    2: large red-and-black European moth; larvae feed on leaves of
       ragwort; introduced into United States to control ragwort
       [syn: cinnabar, cinnabar moth, Callimorpha jacobeae]