'heads-up' definitions:
Definition of 'heads-up'
From: WordNet
adjective
Fully alert and watchful; "played heads-up ball" [syn: heads-up, wide-awake]
noun
A warning message; "he sent a heads-up to the District Attorney"
Definition of 'heads-up'
From: GCIDE
- heads-up \heads-up\ adj. maintaining presence of mind; alert and attentive; able to recognize and take quick advantage of opportunities; resourceful; as, he played good heads-up baseball.
- Syn: wide-awake. [WordNet 1.5]
Definition of 'heads-up'
From: GCIDE
- heads-up \heads-up\ n. [From its use as an interjection to warn of impending danger.] a warning to be prepared for an imminent event. [PJC]