adjective

• (toxicology, pharmacology) Having a chemical nature that is harmful to health or lethal if consumed or otherwise entering into the body in sufficient quantities.
• (medicine) Appearing grossly unwell; characterised by serious, potentially life-threatening compromise in the respiratory, circulatory or other body systems.
• (figurative) Severely negative or harmful.
• (figurative, of a person) Hateful or strongly antipathetic.