ar ‧ se ‧ nic /ˈɑːs ə nɪk $ ˈɑːr-/ BrE AmE noun [uncountable]
[ Date: 1300-1400 ; Language: Latin ; Origin: arsenicum , from Greek arsenikon yellow mineral from which arsenic is obtained, from Syriac zarnig ]
a strong poison. It is a chemical ↑ element : symbol As