1. Of, or containing arsenic with a valence of 5.
1. a white powdered poisonous trioxide of arsenic; used in manufacturing glass and as a pesticide (rat poison) and weed killer
Similar word(s): ratsbane
2. a very poisonous metallic element that has three allotropic forms; arsenic and arsenic compounds are used as herbicides and insecticides and various alloys; found in arsenopyrite and orpiment and realgar