Step outside early on a chilly morning and you’ll see rime — the crisp white frost that covers grass, leaves, cars, and street signs. Also called “hoarfrost,” it forms when water vapor in the air rapidly freezes. “Rime” is an old word — it comes from the Old English “hrīm,” and is related to the Dutch word “rijm.” The simple word was very popular in 18th- and 19th-century literary use. Perhaps the most famous example is Samuel Taylor Coleridge’s “The Rime of the Ancient Mariner” (1834). The word isn’t used at all in the text of the poem, but it serves double duty in the title to inform the theme of icy seas and frost plaguing the Mariner’s journey and as a play on words between “rime” and “rhyme.”