Arsenious

1. a. Pertaining to, or derived from, arsenic, when having an equivalence next lower than the highest; as, arsenious acid.
2. a. Pertaining to, consisting of, or containing, arsenic; as, arsenious powder or glass.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.