The Collaborative International Dictionary of English v.0.48:

Tartarous \Tar"tar*ous\, a. [Cf. F. tartareux.]
   Containing tartar; consisting of tartar, or partaking of its
   qualities; tartareous.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Tartarous \Tar"tar*ous\, a.
   Resembling, or characteristic of, a Tartar; ill-natured;
   irritable.
   [1913 Webster]

         The Tartarous moods of common men.       --B. Jonson.
   [1913 Webster]