'Toxic' definitions:

Definition of 'toxic'

From: WordNet
adjective
Of or relating to or caused by a toxin or poison; "suffering from exposure to toxic substances" [ant: atoxic, nontoxic]

Definition of 'Toxic'

From: GCIDE
  • Toxic \Tox"ic\, Toxical \Tox"ic*al\, a. [L. toxicum poison, originally, a poison in which arrows were dipped, Gr. toxiko`n (sc. ?) poison for smearing arrows with, fr. toxiko`s of or for the bow, from to`xon bow, arrow. Cf. Intoxicate.] Of or pertaining to poison; poisonous; as, toxic medicines. [1913 Webster]