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.
Although painstaking, this work is helping scientists piece together why certain tumors become much more dangerous than others.
From Science Daily ● Oct. 15, 2026
The European Commission gained new regulatory powers in August under the AI Act, the world's most far-reaching rules to curb potentially dangerous uses of the technology.
From Barron's ● Oct. 14, 2026
We still use decades-old technology to detect the presence of dangerous pathogens.
From The Wall Street Journal ● Oct. 14, 2026
Red flag warnings are in place Thursday morning for what officials say could be dangerous Santa Ana winds.
From Los Angeles Times ● Oct. 14, 2026
It was a little crazy, and dangerous perhaps, but I had to do something.
From "Rump: The (Fairly) True Story of Rumpelstilskin" by Liesl Shurtliff
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.
