A rainbow or colorful arc formed in sea foam or spray, similar to a regular rainbow but created by light refracting through water droplets in foam.
From 'foam' + 'bow' (as in rainbow), a compound word combining foam (from Old English 'fam' meaning froth) with bow (from Old English 'boga' meaning arc or curve).
Foambows are real optical phenomena that surfers and coastal people see, but they're so rare in literature that most people have never heard the word—yet the thing itself is more common than rainbows in some coastal areas.
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