(uncountable) the colour blue (as a whole) / (countable) a particular tone of blue / (countable) a particular tone of blue; (heraldry) azure; blue in heraldry / (generally uncountable) a vast blue area, especially:; the sky / (generally uncountable) a vast blue area, especially:; the sea

blue / drunk / bruised

Prussian blue

to (illegally) stop working for one day

(simile) drunk as a fiddler

(idiomatic) to make a promise that cannot be fulfilled. (literally: to promise [someone] the Blue out of the Blue Sky)

blueberry

plural of Blaubeere "blueberries"

Chilean eagle, Black-chested buzzard-eagle

nominative/accusative/genitive plural of Blaubussard