The term hazardous refers to something that poses a significant risk or danger, either through its potential for physical harm or because it is unstable and capable of causing damage. In other words, anything that has the ability to cause injury, illness, property damage, or environmental degradation can be considered hazardous. This term is commonly used in reference to materials, substances, or situations that present a threat to human health or safety, such as chemicals, radioactive waste, explosives, and contaminated sites.