adjective
bluer; bluest
having the color of the clear sky
sad or unhappy
blue in the face
If you do something until you are blue in the face, you do it for a very long time without having any success or making any difference.
blue with cold
or blue from the cold
chiefly Brit of a person or body part :blue from being exposed to cold for too long
go blue
Brit :to turn blue from being cold or not breathing
talk a blue streak
US :to talk rapidly and without stopping
noun
plural blues
the color of the clear sky [noncount]
see color picture
the blue literary :the sky or the sea
out of the blue
without warning :in a surprising or unexpected way