arsenic (n.) Look up arsenic at Dictionary.com
late 14c., from Old French arsenic, from Latin arsenicum, from late Greek arsenikon "arsenic" (Dioscorides; Aristotle has it as sandarake), adapted from Syriac (al) zarniqa "arsenic," from Middle Persian zarnik "gold-colored" (arsenic trisulphide has a lemon-yellow color), from Old Iranian *zarna- "golden," from PIE root *ghel- "to shine" (see Chloe).

The form of the Greek word is folk etymology, literally "masculine," from arsen "male, strong, virile" (cf. arseno-koites "lying with men" in New Testament) supposedly in reference to the powerful properties of the substance. The mineral (as opposed to the element) is properly orpiment, from Latin auri pigmentum, so called because it was used to make golden dyes.