blue

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The hue of that portion of the visible spectrum lying between green and indigo, evoked in the human observer by radiant energy with wavelengths of approximately 420 to 490 nanometers; any of a group of colors that may vary in lightness and saturation, whose hue is that of a clear daytime sky; one of the additive or light primaries; one of the psychological primary hues.
• noun A pigment or dye imparting this hue.
• noun Bluing.
• noun An object having this hue.
• noun Dress or clothing of this hue.
• noun A person who wears a blue uniform.
• noun A dress blue uniform, especially that of the US Army.
• noun A member of the Union Army in the Civil War.
• noun The Union Army.
• noun A bluefish.
• noun Any of various small blue butterflies of the family Lycaenidae.
• noun The sky.
• noun The sea.
• adjective Of the color blue.
• adjective Bluish or having parts that are blue or bluish, as the blue spruce and the blue whale.
• adjective Having a gray or purplish color, as from cold or contusion.
• adjective Wearing blue.
• adjective Being a trail, as for skiing, marked with a sign having a blue square, indicating an intermediate level of difficulty.
• adjective Relating to or being a blue state.
• adjective Gloomy; depressed. synonym: depressed.
• adjective Dismal; dreary.
• adjective Puritanical; strict.
• adjective Aristocratic; patrician.
• adjective Indecent; risqué.
• transitive & intransitive verb To make or become blue.
• idiom (blue in the face) At the point of extreme exasperation.
• idiom (into the blue) At a far distance; into the unknown.
• idiom (out of the blue) From an unexpected or unforeseen source.
• idiom (out of the blue) At a completely unexpected time.

from The Century Dictionary.

• noun In archery: The third circle of the target, which is now usually colored blue. See target.
• noun An arrow which hits this circle; a hit in the blue. By the present method of scoring, such a hit counts 5.
• noun A name sometimes given to water-soluble induline.
• noun Same as bleu-de-roi (which see).
• noun A mixture of methylene-blue and methyl-violet.
• To make blue; dye a blue color; color with bluing; make blue by heating, as metals, etc.
• To blush.
• Of the color of the clear sky; of the color of the spectrum between wave-lengths .505 and .415 micron, and more especially .487 to .460, or of such light mixed with white; azure; cerulean.
• Livid; lead-colored: said of the skin or complexion as affected by cold, contusion, or fear (see blae): hence the phrase black and blue. See black.
• Figuratively, afflicted with low spirits; despondent; depressed; hypochondriacal; having the blues.
• Dismal; unpromising: applied to things: as, a blue lookout.
• Inflexible; rigid; strict in morals or religion; puritanic: as, a blue Presbyterian: often in the form true blue (which see, below).
• [With ref. to blue-stocking, q. v.] Learned; pedantic: applied to women.
• Indecent; obscene: as, blue stories.
• In Australia, the volcanic (basaltic) material in places overlying the Tertiary auriferous gravels.