Definition of Arsenic

Noun: arsenic aa(r)-su-nik

A white powdered poisonous trioxide of arsenic; used in manufacturing glass and as a pesticide (rat poison) and weed killer
- arsenic trioxide, arsenous anhydride, arsenous oxide, white arsenic, ratsbane
A very poisonous metallic element that has three allotropic forms; arsenic and arsenic compounds are used as herbicides and insecticides and in various alloys; found in arsenopyrite and orpiment and realgar
- As, atomic number 33