arsenious
adjective
ar·se·ni·ous är-ˈsē-nē-əs 
: of, relating to, or containing arsenic especially when trivalent
Word History
Etymology
borrowed from French arsénieux, from arsenic arsenic entry 1 + -ieux -ious
First Known Use
1796, in the meaning defined above
Medical Definition
arsenious
adjective
ar·se·ni·ous är-ˈsē-nē-əs
variants also arsenous
ˈärs-nəs, -ᵊn-əs
: of, relating to, or containing arsenic especially when trivalent