arsenic

English arsenic comes from Middle English arsenik, via Middle French arsenic and Latin arsenicum, from Greek arsenikón, 'yellow arsenic,' which was shaped by the similar-sounding Greek word arsenikós, 'potent, virile.' Behind the Greek word lies a Semitic borrowing (compare Aramaic zarnīḵā), tracing back to Middle Iranian *zarnīk and Old Median *zaraniyakā, both meaning 'golden.'

The word began as a term for gold or golden things in Old Median and Iranian languages, then narrowed in Greek to name the yellow mineral 'yellow arsenic,' with its sound reshaped by an unrelated Greek word for potency. From Greek it passed through Latin and French into English essentially unchanged in meaning, naming the element and its poison.

It shares its deep root with the English word 'yellow,' both descending from the same Proto-Indo-European root meaning 'yellow' or 'gold.'