per·​il·​ous ˈper-ə-ləs How to pronounce perilous (audio)
: full of or involving peril
a perilous journey
perilously adverb
perilousness noun
Choose the Right Synonym for perilous

dangerous, hazardous, precarious, perilous, risky mean bringing or involving the chance of loss or injury.

dangerous applies to something that may cause harm or loss unless dealt with carefully.

soldiers on a dangerous mission

hazardous implies great and continuous risk of harm or failure.

claims that smoking is hazardous to your health

precarious suggests both insecurity and uncertainty.

earned a precarious living by gambling

perilous strongly implies the immediacy of danger.

perilous mountain roads

risky often applies to a known and accepted danger.

shied away from risky investments

Example Sentences

a perilous journey across the mountains a perilous journey through hostile territory
Recent Examples on the Web The icefall is a particularly deadly section that becomes even more perilous later in the day as the sun warms the mountain, leading to avalanches, rockfalls and collapsing ice towers. Margaret Osborne, Smithsonian Magazine, 2 June 2023 Though just over one-third of the way into their schedule and in possession of a respectable 29-27 record, the Sox are in a perilous position. Alex Speier,, 2 June 2023 With one episode taking place in an alternate 1969, following two men on a perilous high-tech mission, while another follows an average present-day woman, stunned to discover her life is the subject of a prestige TV drama. Shania Russell,, 31 May 2023 Again heightening the stakes, the harsh environment of outer (or lunar or planetary) space renders malicious cyber theats that much more perilous for crew members. IEEE Spectrum, 31 May 2023 That combination means cities already vulnerable to sea-level rise may also struggle under their own weight—and while much of New York City benefits from strong bedrock, other cities are on more perilous footing. Meghan Bartels, Scientific American, 26 May 2023 Their frequent searches and scrolling — complicated by often spotty cell service and a need to preserve their dwindling batteries — underscore how social media and technology have made migration into the U.S. more accessible but also, in ways, more perilous. Marisa Gerber, Los Angeles Times, 17 May 2023 Despite the risks, thousands of migrants still make the perilous journey to the U.S. each day. Anne Laurent, ABC News, 17 May 2023 Because electoral politics is supposed to be insulated from law enforcement absent evidence that a serious crime or perilous threat to national security is afoot, the FBI is expected to tread lightly, especially in the invocation of its foreign counterintelligence powers. The Editors, National Review, 16 May 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'perilous.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Middle English perilous, perelous, borrowed from Anglo-French perilleus, perillous, going back to Latin perīculōsus, from perīculum "test, risk, peril entry 1" + -ōsus -ous

First Known Use

14th century, in the meaning defined above

Time Traveler
The first known use of perilous was in the 14th century

Dictionary Entries Near perilous

Cite this Entry

“Perilous.” Dictionary, Merriam-Webster, Accessed 10 Jun. 2023.

Kids Definition


per·​il·​ous ˈper-ə-ləs How to pronounce perilous (audio)
: full of or involving peril
perilously adverb
perilousness noun

More from Merriam-Webster on perilous

Last Updated: - Updated example sentences
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