hazardous

adjective

haz·​ard·​ous ˈha-zər-dəs How to pronounce hazardous (audio)
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
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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
For this alert, officials have cited persistent high winds and wave action as the drivers of hazardous swimming conditions, which present significant risks even to experienced swimmers. Anna Skinner, MSNBC Newsweek, 30 Sep. 2025 Remain out of the water to avoid hazardous swimming conditions. Nc Weather Bot, Charlotte Observer, 30 Sep. 2025 Cosmetics retailer Sephora has agreed to pay $775,000 to Sacramento County and nearly two-dozen more California cities and counties for improperly handling hazardous waste at its retail operations, said Sacramento County District Attorney’s officials. Darrell Smith, Sacbee.com, 29 Sep. 2025 The debris flow landslides hurled chunks of railroad tracks, houses and hazardous material into the river. Rolando Arrieta, NPR, 29 Sep. 2025 See All Example Sentences for hazardous

Word History

Etymology

see hazard entry 1

First Known Use

1549, in the meaning defined at sense 1

Time Traveler
The first known use of hazardous was in 1549

Browse Nearby Words

Cite this Entry

“Hazardous.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/hazardous. Accessed 1 Oct. 2025.

Kids Definition

hazardous

adjective
haz·​ard·​ous ˈhaz-ərd-əs How to pronounce hazardous (audio)
hazardously adverb
hazardousness noun

Legal Definition

hazardous

adjective
haz·​ard·​ous
: creating a hazard : involving or exposing one to risk (as of loss or harm)
a hazardous occupation
a hazardous substance
hazardously adverb

More from Merriam-Webster on hazardous

Last Updated: - Updated example sentences
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