red

red a colour at the end of the spectrum next to orange and opposite violet, as the colour of blood, fire, or rubies. As a liturgical colour, red is used for Passion Sunday and Pentecost, and for the feasts of martyrs; figuratively it is associated with the emotions of anger and embarrassment, and in political terms is the colour of radicalism.

Recorded from Old English (as rēad), the word is of Germanic origin, from an Indo-European root shared by Latin rufus, Greek eruthros, and Sanskrit rudhira ‘red’.
Red Army originally, the army of the Bolsheviks, the Workers' and Peasants' Red Army; later, the army of the Soviet Union, formed after the Revolution of 1917. The name was officially dropped in 1946. Red Army has also been used for the army of China or some other Communist countries. The Red Army Faction was a left-wing terrorist group in former West Germany, active from 1968 onwards. It was originally led by Andreas Baader (1943–77) and Ulrike Meinhof (1934–76), and was also called the Baader-Meinhof Group.
Red Arrows in the UK, the aerobatic display team of the Royal Air Force.
Red Baron a nickname for the German fighter pilot Manfred, Freiherr von Richthofen (1882–1918), who flew a distinctive bright red aircraft.
red box in the UK, a box, typically covered with red leather, used by a Minister of State to hold official documents.
Red Branch in Irish epic tradition, the name (translating Gaelic Craebh Ruaid) of the most famous of the royal houses of Ulster; the House of the Red Branch at the capital of Emain Macha was the place where the arms of defeated enemies were stored.
Red Brigades an extreme left-wing terrorist organization based in Italy, which from the early 1970s was responsible for carrying out kidnappings, murders, and acts of sabotage.
red card in soccer and some other games, shown by the referee to a player who is being sent off the field.
red carpet a long, narrow red carpet laid on the ground for a distinguished visitor to walk along when arriving.
red cent the smallest amount of money (the US one-cent coin was formerly made of copper).
Red Crescent a national branch in Muslim countries of the International Movement of the Red Cross and the Red Crescent. The name was adopted in 1906.
red cross an upright red cross on a white ground; the symbol of St George, especially as the national emblem of England, and as the badge and emblem of Christian forces in the Crusades. In the 17th century, the sign of a red cross was placed on the door of a house to indicate the presence within the house of plague; in the mid 19th century, it was taken as the internationally agreed badge of a nursing and ambulance service, when the Red Cross was set up in 1864 at the instigation of the Swiss philanthropist Henri Dunant (1828–1910).
red dragon in heraldry, the badge of Wales, also known as the red dragon of Cadwallader.
red ensign a red flag with the Union Jack in the top corner next to the flagstaff, flown by British-registered ships. It is informally known as the red duster.
red-eye flight a flight (chiefly in North America) on which a passenger cannot expect to get much sleep on account of the time of departure or arrival, especially when a time zone is crossed. In the late 1980s, with transatlantic commuting a reality, it became a fashionable term among British business executives for the overnight flight from New York to London.
red flag the symbol of socialist revolution or a warning of danger; the anthem of Britain's Labour Party, a socialist song with words written in 1889 by the Irish socialist James M. Connell (1852–1929) and sung to the tune of the German song ‘O Tannenbaum’. In Britain, the song is still sung at the conclusion of the annual Labour Party Conference.
red hand the arms or badge of Ulster, a red left hand (also called bloody hand) cut off squarely at the wrist, originally a badge of the O'Neill family.
red hat a cardinal's hat, especially as the symbol of a cardinal's office; in Christian art, a red hat is often shown in depictions of St Jerome as a Doctor of the Church.
red herring something, especially a clue, which is or is intended to be misleading or distracting (so named from the practice of using the scent of a dried smoked herring in training hounds).
Red Indian an old-fashioned term for an American Indian. First recorded in the early 19th century, it has largely fallen out of use, being associated with an earlier period and the corresponding stereotypes of cowboys and Indians and the Wild West.
red-letter day a day that is pleasantly noteworthy or memorable, from the practice of highlighting a saint's day or other festival in red on an ecclesiastical calendar. The term is recorded from the early 18th century.
red-light district an area of a town or city containing many brothels, strip clubs, and other sex businesses, from the use of a red light as the sign of a brothel.
Red Power a movement in support of rights and political power for American Indians.
Red Queen a main character in Lewis Carroll' Through the Looking Glass (1871), who tells Alice that ‘it takes all the running you can do to stay in the same place’.

The Red Queen hypothesis is the hypothesis that organisms are constantly struggling to keep up with one another in an evolutionary race between predator and prey species, named from Lewis Carroll' Red Queen.
red rag to a bull an object, utterance, or act which is certain to provoke someone, from the traditional belief (recorded from the late 16th century) that this colour is particularly irritating to the animal.
red rose tradionally the emblem of the House of Lancaster (as opposed to the white rose of the Yorkists. In the late 20th century, a red rose has also been used as a symbol of the British Labour Party.
red route denoting a scheme intended to facilitate the smooth flow of urban traffic by the imposition of severe penalties for stopping and parking along roads marked with a red line, introduced in Britain in the 1990s.
Red Sea a long, narrow landlocked sea separating Africa from the Arabian peninsula, and now linked to the Indian Ocean in the south by the Gulf of Aden and to the Mediterranean in the north by the Suez Canal. In the biblical account, the Israelites led by Moses escaped from Egypt when the waters of the Red Sea were miraculously parted; the army and chariots of the pursuing Egyptians were drowned when the waters once more closed over them. The name here should properly be translated ‘Sea, or Lake, of Reeds’; it may in fact refer to the marshes of Lake Timsah, now part of the Suez Canal.
red shift in astronomy, the displacement of spectral lines towards longer wavelengths (the red end of the spectrum) in radiation from distant galaxies and celestial objects.
red sky at night, shepherd's delight; red sky in the morning, shepherd's warning proverbial saying, late 14th century, meaning that good and bad weather respectively is presaged by a red sky at sunset and dawn. Ultimately of biblical allusion to Matthew 26:2, ‘When it is evening, yes say, It will be fair weather: for the sky is red. And in the morning, It will be foul weather today: for the sky is red and louring.’
Red Square a large square in Moscow next to the Kremlin. In existence since the late 15th century, under Communism the square was the scene of great parades celebrating May Day and the October Revolution.
red tape a term for excessive bureaucracy or adherence to rules and formalities, especially in public business; the expression refers to the reddish-pink tape which is commonly used for securing legal and official documents.