1. noun /ˈɑː(ɹ).sə.nɪk,ˈɑɹsənɪk,ɑː(ɹ)ˈsɛnɪk,ɑɹˈsɛnɪk/
b) Arsenic trioxide.
See Also: arsenical, arsenicosis, arsenicum album, arsenous, arsphenamine, neoarsphenamine, neosalvarsan, sulfarsin, sulpharsin
2. adjective /ˈɑː(ɹ).sə.nɪk,ˈɑɹsənɪk,ɑː(ɹ)ˈsɛnɪk,ɑɹˈsɛnɪk/
Of, or containing arsenic with a valence of 5.
Wikipedia foundation.