1. (

• arsenic ,
• arsenic_trioxide ,
• arsenous_anhydride ,
• arsenous_oxide ,
• white_arsenic ,
• ratsbane

) a white powdered poisonous trioxide of arsenic; used in manufacturing glass and as a pesticide (rat poison) and weed killer ;

2. (

• arsenic ,
• As ,
• atomic_number_ ,

) 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 ;