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

• dangerous
• grave
• grievous
• jeopardizing
• menacing
• parlous
• perilous
• risky
• serious
• threatening
• unhealthy
• unsafe
• venturesome

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

Earlier this month, Guatemala's National Institute of Seismology, Volcanology, Meteorology, and Hydrology reported a major uptick in eruptions, prompting the U.S. Embassy in Guatemala to issue a warning on March 11 about hazardous conditions. —Josh Hammer, Newsweek, 19 Mar. 2025

However, no hazardous weather is expected this weekend through midweek. —Robert A. Cronkleton, Kansas City Star, 19 Mar. 2025

Before the hatch is opened, crews will do a final inspection of the spacecraft to make sure no hazardous materials are present. —NBC News, 19 Mar. 2025

This may result in slick and hazardous driving conditions. —Ca Weather Bot, Sacramento Bee, 17 Mar. 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