haz·​ard·​ous | \ ˈha-zər-dəs How to pronounce hazardous (audio) \

Definition of hazardous

1 : involving or exposing one to risk (as of loss or harm) a hazardous occupation disposing of hazardous waste
2 : depending on the effect of unpredictable and unanalyzable forces in determining events : depending on hazard (see hazard entry 1 sense 2a) or chance hazardous outcomes

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Other Words from hazardous

hazardously adverb
hazardousness noun

Choose the Right Synonym for hazardous

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

Examples of hazardous in a Sentence

It was a hazardous voyage. These are hazardous chemicals that can cause death if inhaled.
Recent Examples on the Web That’s a lot more complicated (if less hazardous) for quantum systems than gliders. Quanta Magazine, "Alchemy Arrives in a Burst of Light," 30 Sep. 2020 Meanwhile, the air was considered hazardous in parts of the North Bay, where multiple wildfires were burning. Trisha Thadani, SFChronicle.com, "Bay Area choked by wildfire smoke and unhealthy air — again," 28 Sep. 2020 Fire danger remains extreme, air quality is bad to hazardous, and last week’s wind storms caused downed trees on roads & other safety problems that need to be cleared. oregonlive, "Oregon wildfire closures Thursday, Sept. 17," 16 Sep. 2020 The Oregon Department of Environmental Quality's Air Quality Index is considered hazardous between 301 and 500. CBS News, "Alaska Air suspends some flights because of wildfire smoke," 15 Sep. 2020 The air quality in Oregon cities west of the Cascades ranged from unhealthy to hazardous on Monday, according to the AirNow Index. Tim Gruver, Washington Examiner, "Governor wants Trump to step up wildfire aid as ten confirmed dead in Oregon," 15 Sep. 2020 The asteroid, which was first identified at Palomar Observatory, California, in 2018, is not considered hazardous. Eric Todisco, PEOPLE.com, "NASA Says an Asteroid Is Projected to Head Towards Earth a Day Before Nov. 3 Election," 23 Aug. 2020 If the nurdles aren’t considered hazardous, DEQ may bow out. Tristan Baurick, NOLA.com, "No cleanup planned as millions of plastic pellets wash up along Mississippi River and flow to the Gulf," 18 Aug. 2020 Nearly 4,400 involved leaks considered hazardous, up 20% from the year before, according to data BGE submitted to federal regulators. Talia Richman, baltimoresun.com, "With hazardous gas leaks on the rise in Baltimore area, some ask whether BGE is replacing old pipes fast enough," 13 Aug. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'hazardous.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of hazardous

1549, in the meaning defined at sense 1

History and Etymology for hazardous

see hazard entry 1

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Time Traveler for hazardous

Time Traveler

The first known use of hazardous was in 1549

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Statistics for hazardous

Last Updated

1 Dec 2020

Cite this Entry

“Hazardous.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/hazardous. Accessed 4 Dec. 2020.

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More Definitions for hazardous


How to pronounce hazardous (audio)

English Language Learners Definition of hazardous

: involving risk or danger


haz·​ard·​ous | \ ˈha-zər-dəs How to pronounce hazardous (audio) \

Kids Definition of hazardous

: dangerous sense 1 hazardous chemicals



Legal Definition of hazardous

: creating a hazard : involving or exposing one to risk (as of loss or harm) a hazardous occupation a hazardous substance

Other Words from hazardous

hazardously adverb

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