<p><strong>Noun</strong></p><ul><li>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 nanometers.</li><li>Synonyms: sapphire, cerulean, azure bluing.</li><li>Something having a blue color: Place the blue next to the red.</li><li>A person who wears blue or is a member of a group characterized by some blue symbol: Tomorrow the blues will play the browns.</li><li>(Often initial capital letter) a member of the Union army in the American Civil War or the army itself.</li><li>Compare gray 1 (def 13).</li><li>Bluestocking.</li><li>Blue ribbon (def 1).</li><li>Any of several blue-winged butterflies of the family Lycaenidae.</li><li>Printing: blueline.</li><li>The blue, the sky, the sea, the remote distance: They've vanished into the blue somewhere.</li></ul><p><strong>Adjective</strong></p><ul><li>Of the color of blue: a blue tie.</li><li>(Initial capital letter) of or relating to the Union army in the American Civil War.</li><li>(Of the skin) discolored by cold, contusion, fear, or vascular collapse.</li><li>Depressed in spirits; dejected; melancholy: She felt blue about not being chosen for the team.</li><li>Synonyms: downcast, glum, sad, dispirited, doleful, morose, unhappy, despondent.</li><li>Antonyms: happy.</li><li>Holding or offering little hope; dismal; bleak: a blue outlook.</li><li>Characterized by or stemming from rigid morals or religion: statutes that were blue and unrealistic.</li><li>Synonyms: strait-laced, puritanical, righteous.</li><li>Marked by blasphemy: The air was blue with oaths.</li><li>(Of an animal's pelage) grayish-blue.</li><li>Indecent; somewhat obscene; risqué: a blue joke or film.</li><li>Politics: relating to, supporting, or belonging to the Democratic Party in the United States; Democratic: Compare red 1 (def 14).</li><li>The county effectively turned blue, with all 38 district judges elected being Democrats.</li><li>British: politically conservative.</li></ul><p><strong>Verb</strong></p><ul><li>(Used with object) blued, blu·ing or blue·ing: to make blue; dye a blue color.</li><li>To tinge with bluing: Don't blue your clothes till the second rinse.</li><li>(Used without object) blued, blu·ing or blue·ing: to become or turn blue.</li></ul>