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

For example, Phoenix allows furniture, large appliances, mattresses, toilets and large amounts of vegetation, but does not pick up tires, loose debris and litter, construction materials or tree trunks longer than four feet, or hazardous material. Jen Fifield, azcentral, "Want bulk trash pickup? You'll have to pay in these 2 metro Phoenix cities," 8 July 2019 No hazardous materials have been found in any envelopes sent to organizers, nor to a similar letter sent to Boston City Hall, officials said Monday. Cynthia Fernandez, BostonGlobe.com, "Organizer of ‘Straight Pride Parade’ says he’s received death threats," 2 July 2019 Two people were possibly exposed to hazardous material Monday at a Facebook mailing facility in Menlo Park, according to multiple reports. Gwendolyn Wu, SFChronicle.com, "Hazardous material reported at Facebook mailing facility in Menlo Park," 1 July 2019 Particularly hard hit will be trucks carrying hazardous materials, which are not permitted to drive through the Vista Ridge Tunnel on U.S. 26 and must take a circuitous route around Portland. oregonlive.com, "Buckle up: Northwest Cornelius Pass Road will close for 11 weeks, expect delays and detours abound," 24 June 2019 None of the envelopes contained hazardous materials, Dallas County health officials determined. Sara Coello, Dallas News, "Man banned from OkCupid pleads guilty to sending white powder, threats to Dallas office," 20 June 2019 Under the Trump administration’s interpretation, the agency only has authority over environmental infractions at individual plants, like chemical spills and improper handling of hazardous materials. Lisa Friedman, New York Times, "E.P.A. Finalizes Its Plan to Replace Obama-Era Climate Rules," 19 June 2019 The demolition expenses include $3.5 million for hazardous materials abatement and various demolition design and administrative work. Jc Reindl, Detroit Free Press, "What will rise at The Joe? No one will say as exterior demolition ramps up," 17 June 2019 The California Department of Forestry and Environmental Protection was working to identify the hazardous material. Fox News, "1 dead, 9 hospitalized after central California hazmat spill," 14 June 2019

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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Statistics for hazardous

Last Updated

13 Jul 2019

Look-up Popularity

Time Traveler for hazardous

The first known use of hazardous was in 1549

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More Definitions for hazardous



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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Comments on hazardous

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