Le mot anglais pour arc-en-ciel est
rainbow

Définition en anglais

rainbow
1. n. (Météorol) Arc-en-ciel.
The rainbow appears when the sun is shining and it is raining. It is caused by the refraction of the light through raindrops. In 1666, Newton explained this phenomenon using a glass prism.
L'arc-en-ciel apparaît lorsqu'il pleut et que le soleil brille. Cela est dû à la réfraction de la lumière à travers les gouttes de pluie. En 1666, Newton a expliqué ce phénomène en utilisant un prisme en verre.
Have faith in your dreams and someday, your rainbow will come smiling through.
Écoute ton rêve et demain le Soleil brillera toujours.
The rainbow's colors are: red, orange, yellow, green, blue, indigo and violet.
Les couleurs de l'arc-en-ciel sont : rouge, orange, jaune, vert, bleu, indigo et violet.
2. adj. Iridescent.
3. v. (Rare) Colorer comme un arc-en-ciel.

Rainbow
1. n. A member of the Rainbow Guides, a Girl Guide movement for younger girls.
2. n. A multicoloured arch in the sky, produced by prismatic refraction of light within droplets of rain in the air.
3. n. Any prismatic refraction of light showing a spectrum of colours.
4. n. (often used with “of”) A wide assortment; a varied multitude.
a rainbow of possibilities
5. n. (figurative) An illusion, mirage.
Many electoral promises are rainbows, vanishing soon after poll day.
6. n. (baseball) A curveball, particularly a slow one.
7. n. (poker slang) In Texas hold 'em or Omaha hold 'em, a flop that contains three different suits.
8. n. Rainbow trout.
9. adj. Multicolored.
10. adj. (attributive, chiefly US) Made up of several races or ethnicities, or (more broadly) of several cultural or ideological factions.
11. adj. (attributive) LGBT.
12. adj. (poker, chiefly of a flop) Composed entirely of different suits.
13. v. To pattern with many colours, like a rainbow.