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 group has opposed a new $250 Visa Integrity Fee and expanded social-media screening requirements for some foreign visitors, warning that higher costs and additional entry hurdles could undermine international travel growth. — Luke Fountain, CNBC, 2 Sep. 2026

The pediatric outbreaks that get flagged don't reflect the true gravity of the HIV crisis, public health experts warn. — Betsy Joles, NPR, 2 Sep. 2026

Big Country Vet Clinic in Abilene warned pet owners Monday after seeing eight snakebite cases in a single day. — Brandi D. Addison, USA Today, 2 Sep. 2026

While there are no general downsides to using a body scrub, the dermatologists warn not to massage them too roughly into skin. — Alanna Martine Kilkeary, Glamour, 2 Sep. 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
• morne
• mourn
• porn
• scorn
• shorn
• sworn
• thorn

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