perilous

adjective

per·​il·​ous ˈper-ə-ləs 

ˈpe-rə-

: full of or involving peril

a perilous journey

perilously adverb

perilousness noun

Synonyms of perilous

• dangerous
• hazardous
• risky
• serious

Choose the Right Synonym for perilous

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 perilous in a Sentence

a perilous journey across the mountains

a perilous journey through hostile territory

Recent Examples on the Web

The film’s narrative kicks into gear when the legendary sun-shooting archer vanishes during a mission to rescue the dying sun, prompting Chang Er to embark on a perilous journey to the moon’s dark side alongside an earthbound bandit who crash-lands into her world. —Naman Ramachandran, Variety, 12 Jan. 2026

Last summer, an Immigration and Customs Enforcement agent found himself in a perilous situation. —Allison Gordon, CNN Money, 9 Jan. 2026

The clock gives humanity just 89 seconds to reverse course, its most perilous setting ever. —Chicago Tribune, Twin Cities, 9 Jan. 2026

Andersen issues a plaintive and impassioned plea for understanding and compassion about the plight and perilous circumstances of refugees. —Randy Myers, Mercury News, 8 Jan. 2026

Word History

Etymology

Middle English perilous, perelous, borrowed from Anglo-French perilleus, perillous, going back to Latin perīculōsus, from perīculum "test, risk, peril entry 1" + -ōsus -ous

First Known Use

14th century, in the meaning defined above

Rhymes for perilous

• carolus
• garrulous
• querulous
• puberulous

Kids Definition

perilous

adjective

per·​il·​ous ˈper-ə-ləs 

: full of or involving peril

perilously adverb

perilousness noun