[ bloo ]
See synonyms for: bluebluesblueness on

  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 nanometers.

  1. something having a blue color: Place the blue next to the red.

  2. a person who wears blue or is a member of a group characterized by some blue symbol: Tomorrow the blues will play the browns.

  3. (often initial capital letter) a member of the Union army in the American Civil War or the army itself.: Compare gray1 (def. 13).

  4. any of several blue-winged butterflies of the family Lycaenidae.

  5. Printing. blueline.

  6. the blue,

    • the sky.

    • the sea.

    • the remote distance: They've vanished into the blue somewhere.

adjective,blu·er, blu·est.
  1. of the color of blue: a blue tie.

  2. (initial capital letter) of or relating to the Union army in the American Civil War.

  1. (of the skin) discolored by cold, contusion, fear, or vascular collapse.

  2. depressed in spirits; dejected; melancholy: She felt blue about not being chosen for the team.

  3. holding or offering little hope; dismal; bleak: a blue outlook.

  4. characterized by or stemming from rigid morals or religion: statutes that were blue and unrealistic.

  5. marked by blasphemy: The air was blue with oaths.

  6. (of an animal's pelage) grayish-blue.

  7. indecent; somewhat obscene; risqué: a blue joke or film.

  8. Politics.

    • relating to, supporting, or belonging to the Democratic Party in the United States; Democratic: The county effectively turned blue, with all 38 district judges elected being Democrats.: Compare red1 (def. 14).

    • British. politically conservative.

verb (used with object),blued, blu·ing or blue·ing.
  1. to make blue; dye a blue color.

  2. to tinge with bluing: Don't blue your clothes till the second rinse.

verb (used without object),blued, blu·ing or blue·ing.
  1. to become or turn blue.

Idioms about blue

  1. 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.

  2. out of the blue, suddenly and unexpectedly: The inheritance came out of the blue as a stroke of good fortune.

Origin of blue

First recorded in 1250–1300; Middle English blewe, from Anglo-French blew, bl(i)u, bl(i)ef “blue, livid, discolored,” Old French blo, blau (French bleu ), from unattested Germanic blǣwaz; compare Old English blǣwen, contraction of blǣhǣwen “deep blue, perse,” Old Frisian blāw, Middle Dutch blā(u), Old High German blāo (German blau ), Old Norse blār

Other words for blue

Opposites for blue

Other words from blue

  • blue·ly, adverb
  • blue·ness, noun
  • half-blue, adjective
  • un·blued, adjective

Words that may be confused with blue

Words Nearby blue Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use blue in a sentence

British Dictionary definitions for blue (1 of 2)


/ (bluː) /

  1. any of a group of colours, such as that of a clear unclouded sky, that have wavelengths in the range 490–445 nanometres. Blue is the complementary colour of yellow and with red and green forms a set of primary colours: Related adjective: cyanic

  2. a dye or pigment of any of these colours

  1. blue cloth or clothing: dressed in blue

    • a sportsperson who represents or has represented Oxford or Cambridge University and has the right to wear the university colour (dark blue for Oxford, light blue for Cambridge): an Oxford blue

    • the honour of so representing one's university

  2. British an informal name for Tory

  3. any of numerous small blue-winged butterflies of the genera Lampides, Polyommatus, etc: family Lycaenidae

  4. archaic short for bluestocking

  5. slang a policeman

  6. archery a blue ring on a target, between the red and the black, scoring five points

  7. a blue ball in snooker, etc

  8. another name for blueing

  9. Australian and NZ slang an argument or fight: he had a blue with a taxi driver

  10. Also: bluey Australian and NZ slang a court summons, esp for a traffic offence

  11. Australian and NZ informal a mistake; error

  12. out of the blue apparently from nowhere; unexpectedly: the opportunity came out of the blue

  13. into the blue into the unknown or the far distance

adjectivebluer or bluest
  1. of the colour blue

  2. (of the flesh) having a purple tinge, as from cold or contusion

  1. depressed, moody, or unhappy

  2. dismal or depressing: a blue day

  3. indecent, titillating, or pornographic: blue films

  4. bluish in colour or having parts or marks that are bluish: a blue fox; a blue whale

  5. rare aristocratic; noble; patrician: a blue family See blue blood

  6. US relating to, supporting, or representing the Democratic Party: Compare red 1 (def. 18)

verbblues, blueing, bluing or blued
  1. to make, dye, or become blue

  2. (tr) to treat (laundry) with blueing

  1. (tr) slang to spend extravagantly or wastefully; squander

Origin of blue

C13: from Old French bleu, of Germanic origin; compare Old Norse blār, Old High German blāo, Middle Dutch blā; related to Latin flāvus yellow

Derived forms of blue

  • bluely, adverb
  • blueness, noun

British Dictionary definitions for Blue (2 of 2)



/ (bluː) /

  1. Australian informal a nickname for a person with red hair

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Idioms and Phrases with blue


In addition to the idioms beginning with blue

  • blue funk, in a
  • blue in the face

also see:

  • between a rock and a hard place (devil and deep blue sea)
  • black and blue
  • bolt from the blue
  • have the blues
  • into thin air (the blue)
  • like greased lightning (a blue streak)
  • once in a blue moon
  • out of a clear blue sky
  • talk one's arm off (a blue streak
  • until blue in the face)

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.