What does dangerous mean?
"Dangerous" is one of English's most versatile words for threat, describing anything able or likely to cause harm, injury, or loss. It applies equally to physical hazards — a dangerous intersection, a dangerous dog — and to abstract risks, such as a dangerous precedent or a dangerous level of debt. The adjective carries no strong connotation of formality, making it at home in legal texts, weather warnings, news reports, and casual conversation alike. It derives through Old French from a Latin root meaning power or lordship, a reminder that its earliest sense involved falling under another's control rather than facing outright violence. Related forms include the noun "danger" and the adverb "dangerously," while near-synonyms such as hazardous, risky, and treacherous allow writers to shade meaning toward chance, recklessness, or hidden menace. Few adjectives are used across such a wide range of contexts, which makes "dangerous" an essential word for describing both the world's evident perils and its subtler threats.
adjectiveAble or likely to cause harm, injury, or death; involving or accompanied by risk or peril.
- Likely to cause harm, injury, or death.
- Involving risk or uncertainty; likely to lead to trouble or undesirable consequences.
"The icy roads were dangerous after midnight, so we waited for daylight to drive."
"It's dangerous to swim here because of the strong currents."
"He made the dangerous assumption that his boss wouldn't check the numbers."
Despite its menacing meaning, "dangerous" descends from the same root as "dominion" — it originally meant being under someone else's power, not facing their knife.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of dangerous
"Dangerous" comes from Middle English, borrowed from Old French "dangereux," derived from "dangier" (danger), the source of the English noun "danger." The Old French term traces back through Vulgar Latin *dominarium, from Latin "dominus" (lord, master), originally conveying the notion of being under another's power or jurisdiction. Over time the sense shifted from subjection to a lord into general exposure to harm, giving the modern meaning. It shares this ultimate root with words like "dominion" and "domineer."
Related word forms
How dangerous is actually used
"Dangerous" is neutral in register and works in both formal and informal contexts. It can describe physical threats (a dangerous animal) as well as figurative ones (a dangerous idea). In British English, "dangerous driving" is a specific legal offence.
Easily confused with dangerous
"Endangered" describes something at risk of being harmed or destroyed (as in an endangered species), while "dangerous" describes something that poses a threat to others.