(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.

(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.

Having blue as its color. / (informal) Depressed, melancholic, sad. / (health care) Having a bluish or purplish shade of the skin due to a lack of oxygen to the normally deep red blood cells.

plural of blueing

(music) To sing in the style of blues music. / (idiomatic, by extension) To complain, especially in order to obtain sympathy for one's own purportedly sad situation.

(music) A musical genre combining elements of blues and rock and roll

plural of blues scale

plural of ice blue

plural of Wedgwood blue

plural of sky blue