warn

[wawrn] /wɔrn/
verb (used with object)
1.
to give notice, advice, or intimation to (a person, group, etc.) of danger, impending evil, possible harm, or anything else unfavorable:
They warned him of a plot against him. She was warned that her life was in danger.
2.
to urge or advise to be careful; caution:
to warn a careless driver.
3.
to admonish or exhort, as to action or conduct:
She warned her employees to be on time.
4.
to notify, advise, or inform:
to warn a person of an intended visit.
5.
to give notice to (a person, group, etc.) to go, keep at a distance, etc. (often followed by away, off, etc.):
A sign warns trespassers off the grounds. A marker warned boats away from the dock.
6.
to give authoritative or formal notice to (someone); order; summon:
to warn a person to appear in court.
verb (used without object)
7.
to give a warning; caution:
to warn of further disasters.
Origin
before 1000; Middle English warnen, Old English warnian; cognate with German warnen. Cf. ware2
Related forms
warner, noun
prewarn, verb (used with object)
rewarn, verb (used with object)
unwarned, adjective
well-warned, adjective
Synonyms
1. forewarn. Warn, caution, admonish imply attempting to prevent another from running into danger or getting into unpleasant or undesirable circumstances. To warn is to speak plainly and usually in strong terms: to warn him about danger and possible penalties. To caution is to advise about necessary precautions, to put one on one's guard about possibly harmful circumstances or conditions, thus emphasizing avoidance of undesirable consequences: to caution him against driving in such weather. Admonish suggests giving earnest, authoritative advice with only tacit references to danger or penalty: to admonish a person for neglecting his duties.
Examples from the web for warn
  • Twitter alerts warn professors who are using too much electricity.
  • But efforts to warn people off drugs are still too timid.
  • Scientists warn that the damage could be irreversible.
  • Its report two years later would bring better regulation but warn about impeding economic growth.
  • And nearly half of them use their phones to call friends to warn them of pop quizzes.
  • But scientists warn that this volcano is extremely unpredictable.
  • The authors warn that the crash will happen again unless governments find ways of compensating for these foibles through policy.
  • Some songbird couples harmonize to warn rival couples away from their territories.
  • Earthquake early-warning networks detect the earliest stages of an earthquake and sound an alarm to warn people of the danger.
  • They'll warn drivers about wrecks on the road ahead and scout alternative routes.
British Dictionary definitions for warn

warn

/wɔːn/
verb
1.
to notify or make (someone) aware of danger, harm, etc
2.
(transitive; often takes a negative and an infinitive) to advise or admonish (someone) as to action, conduct, etc: I warn you not to do that again
3.
(takes a clause as object or an infinitive) to inform (someone) in advance: he warned them that he would arrive late
4.
(transitive; usually foll by away, off, etc) to give notice to go away, be off, etc: he warned the trespassers off his ground
Derived Forms
warner, noun
Word Origin
Old English wearnian; related to Old High German warnēn, Old Norse varna to refuse
Word Origin and History for warn
v.

Old English warnian "to give notice of impending danger," also intransitive, "to take heed," from West Germanic *warnojanan (cf. Old Norse varna "to admonish," Old High German warnon "to take heed," German warnen "to warn"); related to Old English wær "aware, cautious" (see wary). Related: Warned; warning.