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

Such conditions prompted several regional avalanche forecast services to issue a severe level 4 warning for much of the last two weeks, with some areas even reaching the most severe level 5 warning, at least for a few days. —Issy Ronald, CNN Money, 22 Feb. 2026

Canada’s embassy in Mexico warned its citizens in Puerto Vallarta to shelter in place and generally to keep a low profile in Jalisco. —Fabiola Sanchez, The Orlando Sentinel, 22 Feb. 2026

Other major airlines like Air Canada, Delta Air Lines and Alaska Airlines warned that flights to the region may be disrupted. —Jordan Parker aviation, Dallas Morning News, 22 Feb. 2026

The Itasca Independent School District in Hill County is warning families after a former high school student was arrested for creating AI‑generated pornography using photos of teachers and students, according to district officials. —Doug Myers, CBS News, 22 Feb. 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