The Collaborative International Dictionary of English v.0.48:

Tellurous \Tel"lu*rous\, a. (Chem.)
   Of or pertaining to tellurium; derived from, or containing,
   tellurium; specifically, designating those compounds in which
   the element has a lower valence as contrasted with telluric
   compounds; as, tellurous acid, which is analogous to
   sulphurous acid.
   [1913 Webster]