The definition of a heads up is an alert or a warning.(noun)
An example of a heads up is when you let your Internet-surfing co-worker know that your boss is about to enter his office.
Heads up is defined as something you shout to get someone's attention.(interjection)
An example of heads up is when you yell at a person who isn't paying attention and who is about to get hit with a frisbee.
See heads-up in Webster's New World College Dictionary
Origin: < interjectional phr. heads up!: see head
See heads-up in American Heritage Dictionary 4
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