noun

1. a silvery-white, brittle, very poisonous chemical element, compounds of which are used in making insecticides, glass, medicines, semiconductors, etc.: symbol, As; at. no., 33
2. loosely arsenic trioxide, AsO, a poisonous compound of arsenic used to exterminate insects and rodents: it is a white powder and has no taste

Etymology: ME < OFr < L arsenicum < Gr arsenikon, yellow orpiment; ult. (? via Syr zarnīk(ā)) < Iran *zarnīk, gold-colored (> Pers zarnīq, arsenic); assoc. in Gr with arsenikos, strong, masculine

adjective