adjective
Other Word Forms
Etymology
Origin of dangerous
First recorded in 1175–1225; Middle English da(u)ngerous “domineering, fraught with danger,” from Old French dangereus “threatening, difficult,” equivalent to dangier ( see danger) + -eus -ous
Explanation
Use the word dangerous to describe anything that can potentially cause serious harm, like a snarling pit bull or an icy, treacherous road. The earliest meaning of the word dangerous was "difficult or arrogant." When Geoffrey Chaucer wrote "The Canterbury Tales" in the 1300s, he used dangerous to mean "hard to please." Gradually the meaning changed, so that by the late fifteenth century, dangerous meant "liable to cause hurt" or "risky." Just as popular were two other danger-related words that we don't use anymore today: dangersome and dangerful, which at the time could be used interchangeably with dangerous.
Vocabulary lists containing dangerous
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
"It's more dangerous to accept the supernatural explanations," he warned, noting that conditions ranging from schizophrenia to Tourette's syndrome were once interpreted as spirit possession.
From Barron's ● Jul. 19, 2026
Continued disruptions in the waterway, the throughway for a fifth of the world’s oil, could pull global oil inventories down to dangerous levels.
From The Wall Street Journal ● Jul. 18, 2026
On Saturday, New York City Mayor Zohran Kwame Mamdani said the city was under a flood advisory and advised residents not to "risk your safety in these dangerous conditions".
From BBC ● Jul. 18, 2026
The illness generally isn’t deadly, but diarrhea—which if untreated may last a month—can cause dangerous dehydration.
From Slate ● Jul. 17, 2026
Hannie would only tell me it was too dangerous for me to be out and send me home.
From "Code Name Kingfisher" by Liz Kessler
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.