1. 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.
2. A pigment or dye imparting this hue.
3. bluing.
4. an object having this hue.
5. dress or clothing of this hue: the ushers wore blue.
6. A person who wears a blue uniform.
7. A dress blue uniform, especially that of the U.S. army.
8. A member of the union army in the civil war.
9. the union army.
10. A bluefish.
11. A small blue butterfly of the family Lycaenidae.
12. the sky.
13. the sea.
14. of the color blue.
15. bluish or having parts that are blue or bluish, as the blue spruce and the blue whale.
16. having a gray or purplish color, as from cold or contusion.
17. wearing blue.
18. gloomy; depressed. see synonyms at depressed.
19. dismal; dreary: a blue day.
20. puritanical; strict.
21. aristocratic; patrician.
22. indecent; risqué: a blue joke; a blue movie.
23. to make or become blue.
24. blue in the face at the point of extreme exasperation: I argued with them until I was blue in the face.
25. into the blue at a far distance; into the unknown: spontaneously take a trip into the blue.
26. out of the blue from an unexpected or unforeseen source: criticism that came out of the blue.
27. out of the blue at a completely unexpected time: a long-unseen friend who appeared out of the blue.

1. having a bluish colour shade.
2. depressed, melancholic, sad.
3. pornographic or profane.
4. supportive of, run by, pertaining to, or dominated by a political party represented by the colour blue. (e.g. the conservatives, the democrats)
5. of the higher-frequency region of the part of the electromagnetic spectrum which is relevant in the specific observation.
6. extra rare; left very raw and cold.
7. possessing a coat of fur that is a shade of gray
8. the colour of the clear sky or the deep sea, between green and violet in the visible spectrum, and one of the primary additive colours for transmitted light; the colour obtained by subtracting red and green from white light using magenta and cyan filters; or any colour resembling this.
9. A blue dye or pigment.
10. any of several processes to protect metal against rust.
11. blue clothing
12. plural A blue uniform. see blues.
13. the sky, literally or figuratively.
14. the ocean; deep waters.
15. anything blue, especially to distinguish it from similar objects differing only in color.
16. one of the colour balls used in snooker with a value of 5 points.
17. any of the blue-winged butterflies of the subfamily Polyommatinae in the family Lycaenidae.
18. A bluefish.
19. an argument.
20. A liquid with an intense blue colour, added to a laundry wash to prevent yellowing of white clothes.
21. a type of firecracker
22. to make or become blue.
23. (metallurgy) to treat the surface of steel so that it is passivated chemically and becomes more resistant to rust.
24. to spend (money) extravagantly; to blow.

1. having the color of the clear sky, or a hue resembling it, whether lighter or darker.
2. pale, without redness or glare, -- said of a flame; hence, of the color of burning brimstone, betokening the presence of ghosts or devils.
3. low in spirits; melancholy.
4. suited to produce low spirits; gloomy in prospect.
5. severe or over strict in morals; gloom; ; suiting one who is over strict in morals; inculcating an impracticable, severe, or gloomy mortality.
6. literary; -- applied to women; -- an abbreviation of bluestocking.
7. one of the seven colors into which the rays of light divide themselves, when refracted through a glass prism; the color of the clear sky, or a color resembling that, whether lighter or darker; a pigment having such color.
8. A pedantic woman; a bluestocking.
9. low spirits; a fit of despondency; melancholy.
10. to make blue; to dye of a blue color; to make blue by heating, as metals, etc.

1. 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.
2. 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.
3. figuratively, afflicted with low spirits; despondent; depressed; hypochondriacal; having the blues.
4. dismal; unpromising: applied to things: as, a blue lookout.
5. inflexible; rigid; strict in morals or religion; puritanic: as, a blue presbyterian: often in the form true blue (which see, below).
6. [with ref. to blue-stocking, q. v.] learned; pedantic: applied to women.
7. indecent; obscene: as, blue stories.
8. in australia, the volcanic (basaltic) material in places overlying the tertiary auriferous gravels.
9. the bluish-colored matrix in which the south african diamonds are often found embedded. it is a kind of breccia.
10. the color of the clear sky or of natural ultramarine, or a shade or a tint resembling it; azure. see I., 1.
11. A dye or pigment of this hue.
12. bluing.
13. the sky; the atmosphere.
14. the sea; the deep sea.
15. A member of a party, or of any company of persons, which has adopted blue as its distinctive color.
16. the heavy winter coat of the deer. see phrase in the blue, below.
17. A butterfly of the family Lycœnidœ, found in great britain and other parts of europe.
18. [short for bluestocking.] A pedantic woman.
19. soluble blue.
20. any blue that is free from violet, and retains a true blue color in artificial light.
21. A somewhat light shade of prussian blue.
22. prussian blue in a pasty state.
23. A prussian blue to which has been added an excess of prussiate of potash. also called ball-blue, navy blue.
24. [capitalized] the name popularly given to the english regiment properly called the royal horse guards, or oxford blues, first mustered in 1661, and so called from their blue uniforms.
25. to make blue; dye a blue color; color with bluing; make blue by heating, as metals, etc.
26. to blush.
27. in archery: the third circle of the target, which is now usually colored blue. see target.
28. an arrow which hits this circle; a hit in the blue. by the present method of scoring, such a hit counts 5.
29. A name sometimes given to water-soluble induline.
30. same as bleu-de-roi (which see).
31. A mixture of methylene-blue and methyl-violet.

1. blue clothing
2. the sky as viewed during daylight
3. turn blue
4. used to signify the union forces in the american civil war (who wore blue uniforms)
5. any of numerous small butterflies of the family Lycaenidae
6. of the color intermediate between green and violet; having a color similar to that of a clear unclouded sky
7. blue color or pigment; resembling the color of the clear sky in the daytime
8. the sodium salt of amobarbital that is used as a barbiturate; used as a sedative and a hypnotic
9. morally rigorous and strict
10. suggestive of sexual impropriety
11. causing dejection
12. characterized by profanity or cursing
13. belonging to or characteristic of the nobility or aristocracy
14. used to whiten laundry or hair or give it a bluish tinge
15. any organization or party whose uniforms or badges are blue
16. filled with melancholy and despondency