rainbow

Etymology

From Middle English reinbowe, reinboȝe, from Old English reġnboga (“rainbow”), from Proto-West Germanic *regnabogō, from Proto-Germanic *regnabugô (“rainbow”), equivalent to rain + bow (“arch”). Cognate with West Frisian reinbôge (“rainbow”), Dutch regenboog (“rainbow”), German Regenbogen (“rainbow”), Danish regnbue (“rainbow”), Swedish regnbåge (“rainbow”), Icelandic regnbogi (“rainbow”).

noun

1. A multicoloured arch in the sky, produced by prismatic refraction of light within droplets of rain in the air.
   Why are there so many songs about rainbows And what's on the other side? Rainbows are visions, but only illusions And rainbows have nothing to hide. 1979, Paul Williams, Kenneth Ascher (lyrics and music), “Rainbow Connection”, performed by Kermit the Frog (Jim Henson)
2. Any prismatic refraction of light showing a spectrum of colours.
3. (often used with “of”) A wide assortment; a varied multitude.
   a rainbow of possibilities
4. (figurative) An illusion; a mirage.
   Many electoral promises are rainbows, vanishing soon after poll day.
5. (baseball) A curveball, particularly a slow one.
6. (poker slang) In Texas hold 'em or Omaha hold 'em, a flop that contains three different suits.
7. Rainbow trout.
   Finally, by actual trial, I have found that I can catch more rainbow by using one fly than with a two or three-fly cast. 1911, Francis R. Steel, “Catching the Rainbow Trout”, in The Outing Magazine, volume 58, page 482
8. (figurative, sometimes derogatory) A person within the LGBT community.
   Oh look, the rainbow came back.

adj

1. Multicolored.
2. (attributive, chiefly US) Made up of several races or ethnicities, or (more broadly) of several cultural or ideological factions.
   That Asian-American actor Thomas Ikeda contributes a pleasingly frantic Panthino would not be considered rainbow enough. 1994, John Simon, Of Dogs, Their Masters, and Others, in New York magazine, September 5 1994, page 51
   He went along with them because the Pack was a rainbow group — two Italian-Americans, a black man, a Jew (Bishop), and a sometime Englishman (Lawford) — and they were making a point. 2006, Anthony Summers, Robbyn Swan, Sinatra: The Life, page 246
   The 1999 June elections led to a surprise change in the governing coalition from the long-term ruling Christian Democrats to a rainbow group of Greens, Liberals, and Socialists. 2007, Melissa Haussman, Birgit Sauer, Gendering the state in the age of globalization, page 67
   […] it seemed to me to be naive indeed for the Liberal Democrats to believe that they could simply enter into a rainbow alliance against the Labour Government. 2007, Hooson, in a Letter to the Western Mail, 19 June 2007, published in Crossing the Rubicon: coalition politics Welsh style by John Osmond, page 28
   Mayawati has succeeded in building a social coalition that inverts the pyramid of caste/class hierarchy by building a rainbow alliance of social groups, now dominated by that greatest underclass of all, namely Dalits. 2008, Bidyut Chakrabarty, Indian politics and society since independence, page 76
3. (attributive) LGBT.
   Similarly, the question of who belongs in such a rainbow alliance isn't set. It can include gay men, lesbians, bisexuals and transgender individuals. It can include people who are 'questioning' which culture they belong to … 2005, Alan McKee, The public sphere: an introduction, page 167
4. (poker, chiefly of a flop) Composed entirely of different suits.
5. (mathematics, cryptography) Of or pertaining to rainbow tables.
   rainbow attack

verb

1. (transitive) To brighten with, or as with, a rainbow; to pattern with the colours of the rainbow.
2. (intransitive) To take the appearance of a rainbow.
   We saw birds and butterflies rainbowing in the sun; lazy lizards crawling in the heat; inguanas blinking on stone wall, with mouth wide open for flies; poisonous snakes, not only carved on walls, but gliding through the grass. 1917, G[ulian] L[ansing] Morrill, The Devil in Mexico, Minneapolis, MN: [?], page 55
3. (climbing">climbing) In climbing">climbing gyms where the rocks to climb are colored to indicate suggested climbing">climbing routes, to climb rocks of different colors, thereby ignoring such routes.
   “She's going to learn to belay while I'm climbing? What if I fall?” “You're not going to fall while rainbowing a 5.8, and besides, she'll catch you.” “I could die.” “That would be tragic,” I said. Kaitlyn crossed her arms. 2016, Kristin Lenz, Art of Holding On and Letting Go, Elephant Rock Books
   called “rainbowing.” Different routes were color coordinated. ... Using hand-me-down equipment and learning as much as she could, Brittany began climbing outdoors. She found like-minded people and joined organizations such as Brown ... 2021, Ann McCallum Staats, Thrill Seekers: 15 Remarkable Women in Extreme Sports, Chicago Review Press