Other forms: warning, warned, warns
To warn somebody is to tell them about a danger before it reaches them, while there is still time to move. A text saying the road is flooded; a yellow sign saying the floor is wet.
You warn somebody ABOUT or OF a danger, and you warn them TO do something or not to do it: I warned him not to touch the wire. Warn is not the same as advise, because a warning is always about something bad coming. The noun is a warning, and it turns up everywhere: a written warning at work, a storm warning, a warning shot. To warn somebody off is to tell them to keep away. And I'm warning you, said slowly, is a threat in polite clothes.
1verbwarnTo tell somebody about a danger or a problem so that they can avoid it.~81%
“A neighbour warned us about the ice on the back steps.”
2verbfirmlyTo tell somebody firmly not to do something, or what will happen if they do.~19%
“The referee warned him twice before showing the card.”
Shares are an estimate: a language model read 16 sentences found in the wild and placed 16 of them on a sense — a count of our sample, not a measurement of English.
Warn comes from Old English warnian, which meant to take heed as much as to tell, from a Proto-Germanic verb warnōną with the same double sense. The root behind it, Proto-Indo-European wer-, meant to be aware and to give heed. So warning began inside the person who was on guard, and only later became something you do to somebody else. German warnen and Swedish varna are the same word.
Proto-Indo-European
*wer- — to be aware; give heed
Proto-Germanic
*warnōną — to warn; take heed
Old English
warnian — to take heed; warn
Middle English
warnen
English, today
warn
Built from
From Middle English warnen, warnien (“to warn; admonish”), from Old English warnian (“to take heed; warn”), from Proto-Germanic warnōną (“to warn; take heed”), from Proto-Indo-European wer- (“to be aware; give heed”). Cognate with Dutch waarnen obsolete, German Low German warnen, German warnen, Swedish varna, Icelandic varna.
Etymology from Wiktionary, CC BY-SA