blue

1 of 3

adjective

ˈblü 

bluer; bluest

1

: of the color whose hue is that of the clear sky : of the color blue (see blue entry 2 sense 1)

a blue jacket

her bright blue eyes

The house is blue with white shutters.

2

a

: bluish

the blue haze of tobacco smoke

b

: discolored by or as if by bruising

blue with cold

c

: bluish gray

a blue cat

3

a

: low in spirits : melancholy

has been feeling blue

b

: marked by low spirits : depressing

a blue funk

things looked blue

4

: wearing blue

the blue team

5

of a woman : learned, intellectual

… the ladies were very blue and well-informed …

—W. M. Thackeray

6

: puritanical

… a blue Sunday city …

—James Street

7

a

: profane, indecent

a blue movie

b

: off-color, risqué

blue jokes

8

music : of, relating to, or used in blues (see blues sense 3)

a blue song

9

US politics : tending to support Democratic candidates or policies

As has become increasingly clear over the past few general elections, with their red states and blue states, an American Presidential campaign is no longer truly national.

—Hendrik Hertzberg

compare purple sense 3, red sense 5

bluely adverb

blueness noun

blue

2 of 3

noun

plural blues

1

: a color whose hue is that of the clear sky or that of the portion of the color spectrum lying between green and violet

Blue is his favorite color.

shades of blue

2

a

: a pigment or dye that colors blue

b

: bluing

adding blue to the laundry

3

a

: blue clothing or cloth

will be wearing blue

b

blues plural : a blue costume or uniform

wearing their dress blues

4

a

: a Union soldier in the American Civil War

b

often capitalized : the Union army

the Blue versus the Gray

5

a(1)

: sky

(2)

: the far distance

disappeared into the blue

b

: sea

6

: a blue object

the horse that won the blue [=blue ribbon]

… is bartered … like a stack of blues [=blue chips] in a Reno casino.

—John Lewis

7

: bluestocking

praised the writings of her fellow blues

8

biology : any of numerous small chiefly blue butterflies (family Lycaenidae)

9

: bluefish

fishing for blues

10

: blue cheese

11

physics : one of the three colors (see color entry 1 sense 15) that quarks have in the theory of quantum chromodynamics

One cannot have a single quark on its own because it would have a color (red, green, or blue). Instead, a red quark has to be joined to a green and a blue quark by a "string" of gluons (red + green + blue = white). Such a triplet constitutes a proton or a neutron.

—Stephen Hawking

blue

3 of 3

verb

blued; blueing or bluing; blues

transitive verb

: to make (something) blue in color: such as

a

: to dye, tint, or paint (something) blue

Last, the generation of the grandmothers, in immaculately blued hair …

—John Updike

Tattoos blued his upper arms.

—Jerry Spinelli

b

: to heat (iron or steel) to about 550 to 600°F (288 to 316°C) so that it acquires a bluish protective coating

the blued barrel of the gun

Between banks shrouded with snow, the river gleamed darkly, like blued steel with gold chips of sunlight dancing on each riffle.

—Pete Bodo

intransitive verb

: to turn blue

their blueing fingers

Phrases

blue in the face

: extremely exasperated

argued until he was blue in the face

out of the blue

: without advance notice : unexpectedly

the job offer came out of the blue

blue the air

informal

: to curse angrily

He sliced the air with his fists and blued the air with his mouth.

—Steve Kelley

I have been stealing my father's copy (of Massachusetts Wildlife) for a long time, but last week he found an issue on my desk and blued the air a bit.

—Stephen King Donovan

Synonyms

Adjective

• bawdy
• coarse
• crude
• dirty
• filthy
• foul
• gross
• gutter
• impure
• indecent
• lascivious
• lewd
• locker-room
• nasty
• obscene
• pornographic
• porny
• profane
• raunchy
• ribald
• smutty
• stag
• trashy
• unprintable
• vulgar
• wanton
• X-rated

Noun

• firmament
• heaven(s)
• high
• sky
• welkin

Examples of blue in a Sentence

Adjective

was shocked at the blue banter on that satellite-radio talk show

a cold, dreary day always leaves me blue

Noun

Her favorite color is blue.

a mixture of blues and greens

They sailed off into the blue.

Recent Examples on the Web

Adjective

Notably, the hues of navy and blue work well together to portray the actor as eloquent in matters of style. —Robyn Mowatt, Essence, 18 Apr. 2025

This new species, found near the summit, is adept at moving through trees and has bright blue skin visible only when inflated. —Stories By Real-Time News Team, With Ai Summarization, Miami Herald, 18 Apr. 2025

Noun

The Cordless Vacuum with the ‘Power of a Dyson’ Is Down to $80 Today — but Not for Long The towels are on sale in multiple colors, including neutrals, pastels, and bright shades, such as dark gray, aqua blue, and yellow, so one is bound to match your bathroom decor. —Toni Sutton, People.com, 19 Apr. 2025

Preacher Boy seems to be loosely based on the legend of real-life blues musician Robert Johnson whose guitar was said to have been tuned by the devil at a crossroads, granting him musical prowess. —Kathleen Newman-Bremang, Refinery29, 18 Apr. 2025

Word History

Etymology

Adjective, Noun, and Verb

Middle English, from Anglo-French blef, blew, of Germanic origin; akin to Old High German blāo blue; akin to Latin flavus yellow

First Known Use

Adjective

13th century, in the meaning defined at sense 1

Noun

14th century, in the meaning defined at sense 1

Verb

1606, in the meaning defined at transitive sense

Phrases Containing blue

• baby blue
• baby blue eyes
• between the devil and the deep blue sea
• black-and-blue
• blue agave
• blue baby
• blue blood
• blue book
• blue catfish
• blue cheese
• blue chip
• blue-chipper
• blue cohosh
• blue-collar
• blue corn
• blue crab
• blue curls
• blue devils
• blue-eyed
• blue-eyed grass
• blue flag
• blue flag iris
• blue flu
• blue from the cold
• blue grama
• blue-green alga
• blue gum
• blue heeler
• blue heron
• blue jay
• blue jeans
• blue law
• blue line
• blue marlin
• blue mold
• blue moon
• blue mussel
• blue note
• blue pencil
• blue peter
• blue pike
• blue plate
• blue point
• blue racer
• blue riband
• blue ribbon
• blue screen
• blue screen of death
• blue shark
• blue sheep
• blue sky
• blue-sky law
• blue spruce
• blue streak
• blue tang
• blue the air
• blue vitriol
• blue water
• blue whale
• blue-winged teal
• blue with cold
• bolt from the blue
• bolt out of the blue
• bromothymol blue
• bromthymol blue
• cobalt blue
• Colorado blue spruce
• cornflower blue
• go blue
• great blue heron
• Kerry blue terrier
• methylene blue
• midnight blue
• navy blue
• once in a blue moon
• out of the blue
• peacock blue
• powder blue
• Prussian blue
• royal blue
• Russian blue
• scream blue murder
• sky blue
• slate blue
• steel blue
• talk a blue streak
• teal blue
• the blue
• toluidine blue
• true blue
• turquoise blue

Rhymes for blue

• blew
• boo
• brew
• chew
• chou
• clue
• coo
• coup
• crew
• cue
• dew
• do

Kids Definition

blue

1 of 3 adjective

ˈblü 

1

: of the color blue

2

: low in spirits : melancholy

3

: tending to support Democratic policies or candidates

blue states

blueness noun

blue

2 of 3 noun

1

: the color of the clear daytime sky or of the colors of light between green and violet

2

: blue clothing or cloth

3

a

: sky sense 1

b

: sea sense 1a

blue

3 of 3 verb

blued; blueing or bluing

: to make or turn blue

Medical Definition

blue

1 of 2 adjective

ˈblü 

bluer; bluest

: of the color blue

blue

2 of 2 noun

1

: a color whose hue is that of the clear sky or that of the portion of the color spectrum lying between green and violet

2

: a pigment or dye that colors blue see prussian blue