warn

verb

ˈwȯrn 

warned; warning; warns

transitive verb

1

a

: to give notice to beforehand especially of danger or evil

b

: to give admonishing advice to : counsel

c

: to call to one's attention : inform

2

: to order to go or stay away

—often used with off

intransitive verb

: to give a warning

warner noun

Synonyms of warn

• alert
• advise

Examples of warn in a Sentence

I had been warned about the difficulties of the job.

She warned me that the stove was still hot.

“This won't be easy,” he warned.

Nobody warned me about the dangers.

I warned him to be careful, but he didn't listen to me.

She warned us not to go too close to the fire.

Recent Examples on the Web

The Supreme Court on April 27 appeared divided over whether Bayer can be sued for failing to warn that the company’s Roundup weed killer may cause cancer, hearing arguments in a major case that could block thousands of lawsuits and shield the company from billions of dollars in potential liability. —Maureen Groppe, USA Today, 28 Apr. 2026

Sweeping up lots of folks Of course, geofencing can sweep up lots of completely innocent people as suspects, and critics warn that geofencing could be used by the government to spy on law-abiding citizens engaging in, among other things, lawful protests and political activity. —Nina Totenberg, NPR, 27 Apr. 2026

Weather officials warned of potentially severe thunderstorms that could bring tornadoes, strong winds and hail to several Illinois counties Monday. —Audrey Pachuta, Chicago Tribune, 27 Apr. 2026

However, the path to commercialization remains rocky; while the central government prepares to open bidding for construction and operations, officials warn of mounting skepticism from the private sector. —Mrigakshi Dixit, Interesting Engineering, 27 Apr. 2026

Word History

Etymology

Middle English warnen, going back to Old English wearnian, warnian "to be on one's guard, make aware, put on one's guard," going back to West Germanic *warnōjan- (whence Middle Dutch waernen "to provide with, give notice of a danger," Old High German warnōn), probably causative derivative of Germanic *wara- "cognizant, watchful" — more at ware entry 1

First Known Use

before the 12th century, in the meaning defined at transitive sense 1a

Phrases Containing warn

• I have to warn you
• pre-warn
• warn off

Rhymes for warn

• borne
• bourn
• bourne
• corn
• morn
• mourn
• porn
• scorn
• shorn
• sworn
• thorn
• torn

Kids Definition

warn

verb

ˈwȯ(ə)rn 

1

a

: to give notice to beforehand especially of danger or evil

b

: to give advice to : counsel

2

: to order to go or stay away

warned us off their land

warner noun