adj

• (informal) Depressed, melancholic, sad.
  "“Heavens!” exclaimed Nina, “the blue-stocking and the fogy!—and yours are pale blue, Eileen!—you’re about as self-conscious as Drina—slumping there with your hair tumbling à la Mérode! Oh, it's very picturesque, of course, but a straight spine and good grooming is better.[…]”"
• (of a flame) Pale, without redness or glare.
  "The candle burns blue."
• (politics) Supportive of, run by (a member of), pertaining to, or dominated by a political party represented by the colour blue.
  "I live in a blue constituency.  Congress turned blue in the mid-term elections."
• (politics) Supportive of, run by (a member of), pertaining to, or dominated by a political party represented by the colour blue.
  "Illawarra turns blue in Liberal washout"

noun

• (countable and uncountable) The colour of the clear sky or the deep sea; the colour midway between green and violet in the visible spectrum and one of the primary additive colours.
  "Lady Penrhyn was quite handsome enough to have spared one ingredient in her cup of fascination, but, unfortunately, having been married in her teens, she expected to live in them, and, never being reminded by the trials to which her sex is subject, of the flight of years, and the inroads of suffering, expected time to stand still, and the first bloom of existence (the blue on the plum) to remain as stationary as her own taste, for the pleasures of flirtation."
• (uncountable) Blue clothing.
  "The boys in blue marched to the pipers."
• (uncountable) Blue clothing.
• (uncountable) Blue clothing.
  "Come on, you blues!"

verb

• (ergative) To make or become blue; to turn blue.
  "It blows, it snows, And blues your nose, My toes are all frost bitten The weather would Quite starve the crows, Or freeze the part you sit on."
• (transitive, metallurgy) To treat the surface of steel so that it is passivated chemically and becomes more resistant to rust.
• (transitive, laundry) To brighten by treating with blue (laundry aid).
• (intransitive, Australia, slang) To fight, brawl, or argue.
  "It was years since Ken had flogged her up, but blueing with him still made her ache."

verb

• (transitive, slang, dated) To spend (money) extravagantly; to blow.
  "They was willing to blue the lot and have nothing left when they got home except debts on the never-never."