(idiomatic) To argue uncompromisingly. / To struggle against something that does not give way.

(chiefly US, idiomatic) A warning or call to pay attention; an advisory notice; a notice of what is to happen; a holler.

With head directly above the neck, eyes front. / Alert; vigilant

(poker) Containing only two players.

Alternative spelling of heads-up

(idiomatic) Used as an informal warning, caution, or call for attention; pay attention!

plural of head of state

(philately) British stamps with the image of King George V, based on a photograph by the court photographers W & D Downey.

plural of chowder head

(idiomatic) The practice of flipping a coin in the air, to choose between two alternatives based on which side lands face up.