noun
: an arsenate of calcium [as the normal tricalcium arsenate Ca 3 (AsO 4 ) 2 or a basic salt 3Ca 3 (AsO 4 ) 2 =Ca(OH) 2 ] ; especially : a commercial mixture obtained as a white powder usually by heating arsenic pentoxide and calcium hydroxide in water and used as an insecticide especially in the form of a dust