rainbow

American  

[reyn-boh] / ˈreɪnˌboʊ /

noun

1. a bow or arc of prismatic colors appearing in the heavens opposite the sun and caused by the refraction and reflection of the sun's rays in drops of rain.

2. a similar bow of colors, especially one appearing in the spray of a waterfall or fountain.

3. any brightly multicolored arrangement or display.

4. a wide variety or range; gamut.

5. a visionary goal.

   He pursued the rainbow of a singing career for years before becoming a success.

6. rainbow trout.

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adjective

1. having a diverse membership; including representatives from different races, ethnicities, genders, sexual orientations, etc.: LGBTQ Pride month celebrates all of the rainbow community.

   Archbishop Desmond Tutu famously described postapartheid South Africa as a rainbow nation.

   LGBTQ Pride month celebrates all of the rainbow community.

   Candidates are appealing to a rainbow coalition of minority voters.

Rainbow ¹ British  

/ ˈreɪnˌbəʊ /

noun

1. a member of the Rainbow Guides, the youngest group of girls (aged 5-7 years) in The Guide Association

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rainbow ² British  

/ ˈreɪnˌbəʊ /

noun

1. a bow-shaped display in the sky of the colours of the spectrum, caused by the refraction and reflection of the sun's rays through rain or mist

2. 1. any similar display of bright colours

   2. ( as modifier )

      a rainbow pattern

3. an illusory hope

   to chase rainbows

4. (modifier) of or relating to a political grouping together by several minorities, esp of different races

   the rainbow coalition

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rainbow Scientific  

/ rān′bō′ /

1. An arc-shaped spectrum of color seen in the sky opposite the Sun, especially after rain, caused by the refraction and reflection of sunlight by droplets of water suspended in the air. Secondary rainbows that are larger and paler sometimes appear within the primary arc with the colors reversed (red being inside). These result from two reflections and refractions of a light ray inside a droplet.

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rainbow Cultural  

1. The colored arch in the sky that is often seen after a rain. The rainbow is formed when water droplets in the air cause the diffraction of sunlight.

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Discover More

The colors of the rainbow are violet, indigo, blue, green, yellow, orange, and red.

Other Word Forms

• rainbowlike adjective
• rainbowy adjective

Etymology

Origin of rainbow

First recorded before 1000; Middle English reinbowe, Old English regnboga, rēnboga; cognate with Old Norse regnbogi, German Regenbogen; rain, bow ²

Explanation

That colorful arc you sometimes see in the sky right after it stops raining? That's a rainbow. The scientific explanation for a rainbow's appearance is that light is refracted in water droplets, briefly revealing the full visible spectrum of light — all of the colors that make it up. While there are actually about a hundred colors in the visible spectrum, we tend to describe a rainbow as having six or seven. In Old English, there were two words for this phenomenon: scurboga, or "shower-bow," proved to be less popular than renboga, "rain bow."

Example Sentences

On the grounds, 2018 was the year “Spectra,” the cylindrical rainbow tower, became part of the festival’s landscape.

From Los Angeles Times • Apr. 6, 2026

"I don't mean rainbow colors, but you know, dark browns or tan colors because that tells us something about the composition, and that tells us something about the history of the Moon."

From Barron's • Apr. 5, 2026

Imagine the emotions of listening to Garland, eyes raised and in a longing voice, singing, “Somewhere over the rainbow, skies are blue…”

From The Wall Street Journal • Mar. 25, 2026

Some, but not all, families see a pot of gold at the end of the rainbow if their child makes it as a professional and heap enormous pressure on their shoulders to succeed.

From BBC • Mar. 20, 2026

The Incorrigibles had decided to sort Miss Mortimer’s books by color, thus making an attractive rainbow pattern on the bookshelves.

From "The Interrupted Tale" by Maryrose Wood