n.1. the pure color of a clear sky; the primary color between green and violet in the visible spectrum, an effect of light with a wavelength between 450 and 500 nm.2. bluing.3. something having a blue color: Place the blue next to the red.4. a person who wears blue or is a member of a group characterized by some blue symbol: Tomorrow the blues will play the browns.5. (often cap.) a member of the Union army in the American Civil War or the army itself. Cf. gray (def. 13).6. bluestocking.8. any of several blue-winged butterflies of the family Lycaenidae.9. Print. blueline.10. the blue,a. the sky.b. the sea.c. the remote distance: They've vanished into the blue somewhere.11. out of the blue, suddenly and unexpectedly: The inheritance came out of the blue as a stroke of good fortune.adj.12. of the color of blue: a blue tie.13. (cap.) of or pertaining to the Union army in the American Civil War.14. (of the skin) discolored by cold, contusion, fear, or vascular collapse.15. depressed in spirits; dejected; melancholy: She felt blue about not being chosen for the team.16. holding or offering little hope; dismal; bleak: a blue outlook.17. characterized by or stemming from rigid morals or religion: statutes that were blue and unrealistic.18. marked by blasphemy: The air was blue with oaths.19. (of an animal's pelage) grayish-blue.20. indecent; somewhat obscene; risqué: a blue joke or film.21. blue in the face, exhausted and speechless, as from excessive anger, physical strain, etc.: I reminded him about it till I was blue in the face.v.t.22. to make blue; dye a blue color.23. to tinge with bluing: Don't blue your clothes till the second rinse.v.i.24. to become or turn blue.[1250-1300; ME blewe < AF blew, bl(i)u, bl(i)ef blue, livid, discolored, OF blo, blau (F bleu) < Gmc *blaewaz; cf. OE blaewen, contr. of blaehaewen deep blue, perse (see BLAE, HUE), OFris blaw, MD bla(u), OHG blao (G blau), ON blar]Syn. 1. azure, cerulean, sapphire. 15. despondent, unhappy, morose, doleful, dispirited, sad, glum, downcast. 16. gloomy, dispiriting. 17. righteous, puritanical, moral, severe, prudish.Ant. 15. happy.
* * *(as used in expressions)blue green algaeblue groundThe Blue Rider
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