A letterman at Oxford or Cambridge.

(historical) A member of the Royal Horse Guards (which merged with the 1st Dragoons in 1969)

Synonym of British Blue (“a breed of cat”)

(countable and uncountable) The colour of the clear sky or the deep sea, between green and purple 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.

Anything coloured blue, especially to distinguish it from similar objects differing only in color.

A blue dye or pigment.

(uncountable) A noun "blue" represents various forms such as blue clothing, a blue uniform, a member of a sports team that wears blue colors, an umpire in baseball, sporting colors awarded for achievement, a person who has received such sporting colors, a member of law enforcement, and a bluestocking.

The sky, literally or figuratively.

The ocean; deep waters.

The far distance; a remote or distant place.

A dog or cat with a slaty gray coat.

(snooker) One of the colour balls used in snooker, with a value of five points.

(entomology) Any of the butterflies of the subfamily Polyommatinae in the family Lycaenidae, most of which have blue on their wings.

A bluefish.

(Australia, colloquial) An argument or brawl.

A liquid with an intense blue colour, added to a laundry wash to prevent yellowing of white clothes.

Any of several processes to protect metal against rust.

(Britain) A type of firecracker.

(particle physics) One of the three color charges for quarks.

(UK) A member or supporter of the Conservative Party.

(ergative) To make or become blue; to turn blue.

(transitive, metallurgy) To treat the surface of steel so that it is passivated chemically and becomes more resistant to rust.

(transitive, laundry) To brighten by treating with blue (laundry aid).

(intransitive, Australia, slang) To fight, brawl, or argue.

Having blue as its color.

(informal) Depressed, melancholic, sad.

Having a bluish or purplish shade of the skin due to a lack of oxygen to the normally deep red blood cells.

Pale, without redness or glare; said of a flame.

(politics) Supportive of, run by, pertaining to, or dominated by a political party represented by the color blue, such as the democratic party in the us, the liberal party in australia, or the conservative party in the uk.

(astronomy) Of the higher-frequency region of the part of the electromagnetic spectrum which is relevant in the specific observation.

(of steak) Extra rare; left very raw and cold.

(of a dog or cat) Having a coat of fur of a slaty gray shade.

(particle physics) Having a color charge of blue.

(informal) Risqué; obscene; profane; pornographic.