dangerous

Dangerous is an adjective used to describe something that can cause harm, injury, damage, or loss. It is applied to people, objects, substances, situations, or activities that present a significant risk. In everyday language, the term signals a warning or the need for caution. Synonyms include hazardous, perilous, and risky; antonyms include safe and harmless.

In safety and law, the term appears in labels (dangerous substances), risk assessments, and safety protocols. Dangerous substances require special handling, storage, and transport. In medicine and biology, dangerous pathogens describe agents that can cause serious illness. Some legal systems use terms such as dangerous offender or dangerous animal to designate individuals or entities posing a threat to public safety.

Examples of contexts described as dangerous include reckless driving, explosives, toxic chemicals, wild or venomous animals, severe weather, unstable infrastructure, and high-risk activities such as high-altitude climbing without proper equipment.

Etymology: dangerous comes from Old French dangereux, via Latin periculosus from danger, with the sense of immediacy and potential for harm. The modern usage emphasizes risk in everyday language as well as in formal safety, regulatory, and public-health contexts.