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primary rainbow

American

noun

the most commonly seen rainbow, formed by light rays that undergo a single internal reflection in a drop of water.

Etymology

Origin of primary rainbow

First recorded in 1785–95

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.