/wɔ:n; wɔrn/
v
1 (a) [Tn, Tn.pr, Dn.f, Dn.w] ~ sb (of sth) give sb notice of sth, esp possible danger or unpleasant consequences; inform sb in advance of what may happen 提醒某人（尤指可能有危险的或有不良後果的事）; 预先通知某人; 警告
*`Mind the step,' she warned. ｀小心脚底下,＇她提醒道.
* I tried to warn him, but he wouldn't listen. 我事先跟他说过, 可他就是不听.
* She has been warned of the danger of driving the car in that state. 已经告诉过她, 汽车这个样子开起来有危险.
* The police are warning (motorists) of possible delays. 警方通知（驾驶汽车的人）交通可能受阻.
* If you warn me in advance, I will have your order ready for you. 你若预先通知我, 我就能给您准备好了.
* They warned her that if she did it again she would be sent to prison. 他们警告她说她再这么干就把她关进监狱.
* I had been warned what to expect. 事先已经告诉过我要出这种事.(b) [Tn.pr] ~ sb about/against sb/sth; ~ sb against doing sth put sb on his guard against sb/sth 让某人警惕或提防某人[某事物]
*He warned us against pickpockets. 他告诉我们要小心扒手.
* The police have warned shopkeepers about the forged banknotes. 警方已通知各店主留意伪钞.
* The doctor warned us against overtiring the patient. 医生让我们注意病人不可过劳.
(c) [Dn.t] advise sb (not) to do sth 建议或劝告某人（不要）做某事
*They were warned not to climb the mountain in such bad weather. 已经劝过他们天气这么坏不要攀登那座山.
* She warned them to be careful. 她告诉他们务必小心.
2 (phr v) warn sb off (sth/doing sth) give sb notice that he must go or stay away, eg from private property 通知某人离开或不要接触（如私人的地方）
*I had been warned off visiting her while she was still unwell. 已经告诉我她还没好不要去看她.

v [I and T]
[Language: Old English;Origin: warnian]
to tell someone that something bad or dangerous may happen, so that they can avoid it or prevent it
　'Be careful, the rocks are slippery,' Alex warned.
warn sb about sth
　Travellers to Africa are being warned about the danger of HIV infection.
warn (sb) of sth
　Salmon farmers are warning of the severe crisis facing the industry.
warn sb (not) to do sth
　I warned you not to walk home alone.
　Motorists are being warned to avoid the centre of London this weekend.
warn sb (that)
　We warned them that there was a bull in the field.
to tell someone about something before it happens so that they are not worried or surprised by it
warn sb (that)
　Warn her you're going to be back late.
warn () against [warn (sb) against sth] phr v
to advise someone not to do something because it may have dangerous or unpleasant results
　Her financial adviser warned her against such a risky investment.
warn (sb) against doing sth
　The police have warned tourists against leaving the main tourist centres.
warn away [warn sb⇔away] phr v
to tell someone that they should not go near something, especially because it may be dangerous
　The snake's markings are intended to warn away predators.
warn sb off [warn sb⇔ off] phr v
to tell people that they should not go near something, especially because it might be dangerous
　Some animals mark their territory to warn off rivals.
especially BrE to tell someone that they should not do or use something because it might be dangerous
warn sb off doing sth
　Doctors should have warned people off using the drug much earlier than they did.