The word "in-noxiousness" refers to something that is harmless or non-toxic. The antonyms, therefore, would be words that describe something that is dangerous, harmful, or toxic. Examples of antonyms for "in-noxiousness" include poisonous, toxic, hazardous, harmful, noxious, injurious, destructive, and lethal. These words are often used to describe substances or situations that can cause harm to living organisms or the environment. It is important to be aware of these antonyms and to take necessary precautions to avoid exposure to harmful substances and situations to ensure safety and well-being.