any of various colors resembling the color of blood; the primary color at one extreme end of the visible spectrum, an effect of light with a wavelength between 610 and 780 nm.
2.
something red.
3.
(often initial capital letter) a radical leftist in politics, especially a communist.
see red, Informal. to become very angry; become enraged: Snobs make her see red.
Origin: before 900; Middle English red,Old English rēad; cognate with German rot,Dutch rood,Old Norse raudhr,Latin rūfus, ruber,Greek erythrós;see rubella, rufescent, erythro-
"Bolshevik," 1917, from red (1), the color they adopted for themselves. Association in Europe of red with revolutionary politics (on notion of blood and violence) is from at least 1297, but got a boost 1793 with adoption of the red Phrygian cap (Fr. bonnet rouge) as symbol of
the Fr. Revolution. First specific political reference in Eng. was 1848 (adj.), in news reports of the Second French Republic (a.k.a. Red Republic). The noun meaning "radical, communist" is from 1851.