Red definition

Having red as its colour.

The girl wore a red skirt.
Of hair, having an orange-brown colour; ginger.

Her hair had red highlights.
Leftwing, socialist or communist.
- "Only Nixon could go to China" was the refrain of conventional wisdom during Richard Nixon’s 1972 official visit to Mao Tse-tung’s regime. Nixon’s anti-communist credentials, however dubious, provided useful camouflage as he opened diplomatic relations with Red China and made breathtaking concessions that an undisguised liberal couldn’t get away with. http://www.thenewamerican.com/tna/1998/vo14no16/vo14no16_dragon.htm
Supportive of or dominated by the Republican Party.

a red state

a red Congress
Of or pertaining to the Republican Party.

a red advertisement
Supportive of the Labour Party.
Of the lower-frequency region of the part of the electromagnetic spectrum which is relevant in the specific observation.

Any of a range of colours having the longest wavelengths, 670nm, 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.
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
The drug secobarbital; a capsule of this drug.
- 1971: The big market, these days, is in Downers. Reds and smack—Seconal and heroin—and a hellbroth of bad domestic grass sprayed with everything from arsenic to horse tranquillizers. — Hunter S. Thompson, Fear and Loathing in Las Vegas (Harper Perennial 2005, p. 202)
a type of firecracker.

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