Alert
Part of speech: adjective
Definition: Attentive; awake; on-guard.
Part of speech: noun
Definition: An alarm. A notification.
Part of speech: verb
Definition: To give warning to.
Example sentence: Remember, science fiction's always been the kind of first level alert to think about things to come. It's easier for an audience to take warnings from sci-fi without feeling that we're preaching to them. Every science fiction movie I have ever seen, any one that's worth its weight in celluloid, warns us about things that ultimately come true.
Alerting
Part of speech: verb
Definition: To give warning to.