harmful or injurious to health or physical well-being: noxious fumes.
2.
morally harmful; corrupting; pernicious: a noxious plan to spread dissension.
Origin: 1605–15; < Latinnoxius harmful, hurtful, injurious, equivalent to nox(a) harm, hurt, injury (akin to nocēre to do harm, inflict injury; see innocent) + -ius-ious
1612, from L. noxius "hurtful, injurious," from noxa "injury, hurt, damage entailing liability" (related to nocere "to hurt," and to nex "slaughter"), from PIE *nek-ro-, causative form of root *nek- "death" (see necro-).