1 to notify or make (someone) aware of danger, harm, etc.
2 tr; 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 tr; usually foll by: away, off, etc. to give notice to go away, be off, etc.
he warned the trespassers off his ground
(Old English wearnian; related to Old High German warnen, Old Norse varna to refuse)
English Collins Dictionary - English Definition & Thesaurus
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