Falling prices may be a 'warning sign' of a recession. [=may indicate that a recession is coming]
There were storm 'warnings' [=warnings that a storm was approaching] issued for the area.
I'm giving you 'fair warning' that you had better not discuss politics at dinner tonight.
(..) Dialogue: Marked=..,Default,NTP,!Effect,-Not like this.\N-Perhaps you should see the nurse. Dialogue: Marked=..,Default,NTP,!Effect,l think it's a warning.\Nlt means danger's coming. Dialogue: Marked=..,Default,NTP,!Effect,-Of course!\N-What is it? (..)2001 Harry Potter and the Sorcerer's Stone
(..) Dialogue: Marked=..,Default,NTP,!Effect,lt should be a lovely day at the zoo.\Nl'm really looking forward to it. Dialogue: Marked=..,Default,NTP,!Effect,l'm warning you now, boy. Dialogue: Marked=..,Default,NTP,!Effect,Any funny business, any at all... Dialogue: Marked=..,Default,NTP,!Effect,Move! (..)2001 Harry Potter and the Sorcerer's Stone