Definition

/ɹɛd/

noun

Any of a range of colours having the longest wavelengths, 670 nm, of the visible spectrum; a primary additive colour for transmitted light: the colour obtained by subtracting green and blue from white light using magenta and yellow filters; the colour of blood, ripe strawberries, etc.
A revolutionary socialist or (most commonly) a Communist; (usually capitalized) a Bolshevik, a supporter of the Bolsheviks in the Russian Civil War.
One of the 15 red balls used in snooker, distinguished from the colours.

adjective

Having red as its color.
“The girl wore a red skirt.”
(of hair) Having an orange-brown or orange-blond colour; ginger.
“Her hair had red highlights.”
(of a card) Of the hearts or diamonds suits. Compare black
“I got two red queens, and he got one of the black queens.”