n.
Pronunciation: ' ärs-nik, ' är-s ə -
Function: noun
Etymology: Middle English arsenik orpiment, from Anglo-French & Latin; Anglo-French, from Latin arsenicum, from Greek arsenikon, arrhenikon, from Syriac zarn ī g, of Iranian origin; akin to Avestan zaranya gold, Sanskrit hari yellowish ― more at YELLOW
Date: 14th century
1 : a trivalent and pentavalent metalloid poisonous element that is commonly metallic steel gray, crystalline, and brittle and is used especially in wood preservatives, alloys, and semiconductors ― see ELEMENT table
2 : a poisonous trioxide As 2 O 3 or As 4 O 6 of arsenic used especially as an insecticide or weed killer ― called also arsenic trioxide