an arc of colored light in the sky caused by refraction of the sun's rays by rain
"After the summer storm cleared, a brilliant rainbow arched across the sky, displaying every color from red to violet."
A multicoloured arch in the sky, produced by prismatic refraction of light within droplets of rain in the air.
"After earning her badge in the local scouting group, Sarah proudly introduced herself as a new Rainbow during the welcome ceremony."
A member of the Rainbow Guides, a Girl Guide movement for younger girls.
In plain English: A rainbow is a colorful arc in the sky that appears when sunlight shines through raindrops.
"The rainbow appeared over the hills after the storm."
To brighten with, or as with, a rainbow; to pattern with the colours of the rainbow.
"The old man's faded suit was finally repaired and patched in vibrant threads that seemed to rainbow his entire appearance."
In plain English: To rainbow something is to make it look like it has colors of a rainbow, usually by shining light through it.
"The sun began to rainbow across the wet pavement after the storm passed."
Usage: Use this verb when describing something being decorated with vibrant stripes that mimic natural rainbows, such as hair dyed in multiple colors. Avoid using it for simple color changes unless those specific hues are arranged in an arc-like spectrum.
Multicolored.
"The old woman wore a rainbow scarf that shimmered in every color under the sunlight."
"The rainbow arch stretched across the sky after the storm."
A census-designated place in San Diego County, California, United States.
"Residents of Rainbow often drive to nearby Oceanside for their weekly farmers market."
The word rainbow comes from Old English, where it literally meant "rain bow." It entered Middle English as a combination of the words for rain and arch to describe the colorful arc seen in the sky.