What does hazardous mean?
Hazardous is an adjective meaning dangerous or potentially harmful. It is used when something has the capacity to cause injury, illness, damage, or other serious consequences, even if harm has not yet occurred. The word commonly appears in safety, legal, technical, environmental, and public-health contexts, as in hazardous waste, hazardous materials, hazardous chemicals, and hazardous working conditions. Unlike the broader term dangerous, hazardous can suggest a more specific or systematically assessed risk involving exposure, toxicity, instability, or other identifiable hazards. It is also common in warnings and official guidance, where its formal and emphatic character makes it suitable for describing substances and situations that require caution. The related noun hazard names a source of danger or risk, while hazardous functions as the adjective describing that risk. Together, the words are useful for distinguishing ordinary potential danger from risks that may cause significant or preventable harm.
adjectiveDangerous or potentially harmful; involving risk, danger, or exposure to harm. It is commonly used to describe substances, conditions, activities, and situations that may cause injury, damage, or other adverse effects.
- Dangerous or potentially harmful; involving risk, danger, or exposure to harm.
"The factory stores several hazardous chemicals in a secured area."
"Smoking is hazardous to your health."
"The construction company issued guidelines for workers in the hazardous environment."
Hazardous begins with “hazard,” a word that once meant chance, not just danger.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does hazardous come from?
Hazardous was formed in English from hazard with the suffix -ous, meaning involving or presenting a hazard. Hazard entered Middle English from Old French hasard and had senses associated with chance, luck, and risk. Its development from an idea of chance or exposure to danger explains the modern emphasis on possible harm.
Related word forms
How hazardous is actually used
Hazardous is common in formal, technical, safety, and legal contexts. It often emphasizes the presence of potential danger and is especially frequent in expressions concerning substances, materials, workplaces, travel, and waste.
Easily confused with hazardous
A danger is a source or situation of possible harm, whereas hazardous is an adjective describing something that presents danger or risk.
Hazard is usually a noun naming a risk or source of danger, while hazardous describes something that is dangerous or potentially harmful.