toxical

/ˈtɑksɪkəl/
adjective
  1. A less common variant of 'toxic', meaning poisonous or harmful. Often used in older or nonstandard English.
    • The chemist warned about the toxical nature of the compound.
    • The old book described the plant's toxical effects on livestock.
    • Some historical texts use 'toxical' to mean the same as 'toxic'.