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

That has left much of the Black Sea very perilous for commercial vessels. — Tim Lister, CNN Money, 3 Nov. 2026

Sean McVay’s decision to keep two kickers on the roster is partially motivated by the Rams’ playoff chances being in perilous place. — Los Angeles Times, 2 Nov. 2026

On a journey to protect the fate of her children, Eliza is thrust into a perilous race through London’s dark underworld, where she is confronted by an unexpected villain. — Desiree Anello, PEOPLE, 2 Nov. 2026

Shockingly, this development isn’t to blame for Arizona’s perilous lack of water. — Gaby Del Valle, The Verge, 29 Oct. 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