Wordnet 3.0
ADJECTIVE (1)
1.
relating to compounds in which arsenic is trivalent;
The Collaborative International Dictionary of English v.0.48:
Arsenious \Ar*se"ni*ous\, a. [Cf. F. ars['e]nieux.]
1. Pertaining to, consisting of, or containing, arsenic; as,
arsenious powder or glass.
[1913 Webster]
2. (Chem.) Pertaining to, or derived from, arsenic, when
having an equivalence next lower than the highest; as,
arsenious acid.
[1913 Webster]
WordNet (r) 3.0 (2006):
arsenious
adj 1: relating to compounds in which arsenic is trivalent