warning (n.)

"notice beforehand of the consequences that will probably follow continuance in some particular course" [Century Dictionary], Old English warnung, verbal noun from warnian (see warn (v.)).

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Definitions of warning from WordNet
warning (n.)
a message informing of danger;
a warning that still more bombs could explode
warning (n.)
cautionary advice about something imminent (especially imminent danger or other unpleasantness);
the warning was to beware of surprises
Synonyms: admonition / monition / word of advice
warning (n.)
notification of something, usually in advance;
they gave little warning of their arrival
she had only had four days' warning before leaving Berlin
warning (adj.)
serving to warn;