Adjective
1. injurious to physical or mental health;
"noxious chemical wastes""noxious ideas"2. able or likely to do harm
3. causing or capable of causing harm;
"too much sun is harmful to the skin""harmful effects of smoking"4. constituting a disadvantage
5. contrary to your interests or welfare;
"adverse circumstances""made a place for themselves under the most untoward conditions"6. tending to cause great harm