Definitions for "heads-up"
A two player poker game or a larger poker tournament that has been reduced to only two poker players.
When only two players are involved in a hand.
A poker event where the number of players at each table is 2.
maintaining presence of mind; alert and attentive; able to recognize and take quick advantage of opportunities; resourceful; as, he played good heads-up baseball.
The command, tells everyone within ear shot that a shell is being moved, and to be alert as it passes nearby.
fully alert and watchful; "played heads-up ball"
(USA) "avvertimento"; heads-up display devices project readings from instruments onto a windscreen or at head height, enabling an aircraft pilot or car driver to see them without looking down
Keywords:  imminent, warning, prepared, event
a warning to be prepared for an imminent event.
Keywords:  rigging, sails, expressions
Expressions Headsails Sails , Rigging