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 hazardous conditions could impact the Friday evening and Monday morning commutes. — Ca Weather Bot, Sacbee.com, 10 Nov. 2026

The feature documentary set in a remote coastal village of Northern Maine, where generations of men have stoically fished the waters in an often-hazardous pursuit of a living, premiered in February at the Berlin Film Festival. — Matthew Carey, Deadline, 10 Nov. 2026

At the Shore, onshore winds could create rough surf, hazardous boating conditions, and some tidal flooding, although the extent of coastal impacts will depend heavily on the storm's track and how long winds remain onshore. — Grant Gilmore, CBS News, 10 Nov. 2026

And previously unseen chemicals hazardous to human health were detected in a quarter of the 49 inhalable products tested by The Times. — Paige St. John, Los Angeles Times, 8 Nov. 2026

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