hazardous

adjective

haz·​ard·​ous ˈha-zər-dəs 

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

Synonyms of hazardous

• dangerous
• perilous
• risky
• serious
• unsafe

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

The insurance research firm said the soaring costs are due in part to rising real estate values as well as homeowners building in areas where wildland and urban areas blend, which is especially hazardous. —Contessa Brewer,dawn Giel, CNBC, 16 Dec. 2025

Those unregulated hazardous substances include liquid waste, friable, asbestos wastes and combustion wastes. —Stuart Dyos, Nashville Tennessean, 16 Dec. 2025

Doubling a border wall could make the region more hazardous for even some of the smaller creatures, Malusa said. —Brandon Loomis, AZCentral.com, 13 Dec. 2025

Level 2 snow emergency Roadways are hazardous due to accumulated, blowing and drifting snow and roads may be very icy. —Aaron Valdez, Cincinnati Enquirer, 13 Dec. 2025

Word History

Etymology

see hazard entry 1

First Known Use

1549, in the meaning defined at sense 1

Rhymes for hazardous

• nonhazardous

Kids Definition

hazardous

adjective

haz·​ard·​ous ˈhaz-ərd-əs 

: dangerous sense 1, risky

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