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

Alongside analysts and external observers warning that Russia’s full-scale invasion could soon enter a more dangerous phase, Ukrainian President Volodymyr Zelenskyy has said that Russian President Vladimir Putin is preparing to escalate the war. — Sam Meredith, CNBC, 27 Aug. 2026

Opponents warn of new barriers to fiscal review California County Superintendents has worked with two Sacramento-area lawmakers on the proposal. — Chaewon Chung updated August 26, Sacbee.com, 26 Aug. 2026

Officials on both sides of the border have warned that the death toll could rise as rescue crews struggle to reach devastated areas, Reuters reported. — Anthony Thompson, USA Today, 26 Aug. 2026

Two people died from measles in Pennsylvania, the state’s first deaths from the disease in 35 years, with experts warning that figure could rise because of falling vaccination rates in the US. — Jeronimo Gonzalez, semafor.com, 26 Aug. 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