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

JPMorgan shares were down after the bank warned of higher-than-expected spending during an industry conference yesterday. —Jim Cramer, CNBC, 10 Dec. 2025

While the move is framed as a protective measure against online harms, experts warn that, for parents, the ban won’t remove responsibility of monitoring their children's online footprint. —Lydia Patrick, MSNBC Newsweek, 10 Dec. 2025

Both experts warn that Minnesotans may not fully grasp the extent of the public-safety crisis, especially in the metro areas where crime is concentrated. —Stepheny Price, FOXNews.com, 10 Dec. 2025

Republicans are grinning at the prospect of a progressive revolt, as Democratic moderates within the party warn that tip-toeing too far to the left could shoo away general election voters. —Phillip M. Bailey, USA Today, 10 Dec. 2025

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