Word of the Day | Merriam-Webster | cerulean adjective \ ce·ru·le·an \ sə-ˈrü-lē-ən. Definition of cerulean: resembling the blue of the sky. Did you know? Cerulean comes from Latin caeruleus, which means "dark blue" and is most likely from caelum, "sky." The first known use of cerulean was in 1599.
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