warn
UK: wɔːn | US: wɔːrn
vt. to inform someone in advance of a possible danger or problem
vt. to advise someone against doing something unwise
vi. to give a cautionary notice (often followed by "of" or "against")
The word "warn" traces back to Old English warnian, meaning "to take heed" or "guard against," derived from Proto-Germanic warnōną. The root war- is linked to vigilance (compare "ward," "wary"), reflecting the idea of alertness to danger. Over time, the meaning shifted from passive observation to active notification of threats. The modern sense of advising caution emerged by the 13th century.
The weather service warns of heavy storms tonight.
She warned him not to trust strangers.
The label warns against exposing the product to sunlight.
He was warned repeatedly but ignored the advice.
Signs warn visitors to stay on the marked trail.