The Collaborative International Dictionary of English v.0.48:

Spectral \Spec"tral\, a.
   1. Of or pertaining to a specter; ghosty.
      [1913 Webster]

            He that feels timid at the spectral form of evil is
            not the man to spread light.          --F. W.
                                                  Robertson.
      [1913 Webster]

   2. (Opt.) Of or pertaining to the spectrum; made by the
      spectrum; as, spectral colors; spectral analysis.
      [1913 Webster]

   Spectral lemur. (Zool.) See Tarsius.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Tarsius \Tar"si*us\, n. [NL. See Tarsus.] (Zool.)
   A genus of nocturnal lemurine mammals having very large eyes
   and ears, a long tail, and very long proximal tarsal bones;
   -- called also malmag, spectral lemur, podji, and
   tarsier.
   [1913 Webster]