blue

/bluː//blu//blɪʊ̯/

noun

1
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.
2
A blue dye or pigment.
3
Any of several processes to protect metal against rust.
4
Blue clothing
“The boys in blue marched to the pipers.”
5
(in the plural) A blue uniform. See blues.
6
A member of law enforcement
7
The sky, literally or figuratively.
“His request for leave came out of the blue.”
8
The ocean; deep waters.
9
The far distance; a remote or distant place.
10
Anything blue, especially to distinguish it from similar objects differing only in color.
11
A dog or cat with a slaty gray coat.
12
One of the colour balls used in snooker, with a value of five points.
13
Any of the butterflies of the subfamily Polyommatinae in the family Lycaenidae, most of which have blue on their wings.
14
A bluefish.
15
An argument.
16
A liquid with an intense blue colour, added to a laundry wash to prevent yellowing of white clothes.
17
A type of firecracker.
18
A bluestocking.
19
One of the three color charges for quarks.

1
To make or become blue.
2
To treat the surface of steel so that it is passivated chemically and becomes more resistant to rust.
3
(laundry) To brighten by treating with blue (laundry aid)
4
To spend (money) extravagantly; to blow.

1
Of the colour blue.
“the deep blue sea”
2
Depressed, melancholic, sad.
3
Pale, without redness or glare; said of a flame.
“The candle burns blue.”
4
Supportive of, run by (a member of), pertaining to, or dominated by a political party represented by the colour blue.
5
Of the higher-frequency region of the part of the electromagnetic spectrum which is relevant in the specific observation.
6
(of steak) Extra rare; left very raw and cold.
7
(of a dog or cat) Having a coat of fur of a slaty gray shade.
8
Severe or overly strict in morals; gloomy.
“blue and sour religionists; blue laws”
9
(of women) literary; bluestockinged.
10
Having a color charge of blue.
11
(entertainment) Risque or obscene
“His material is too blue for prime-time”