ZARF

In Sunday's Boston Globe Puzzle, 1 across is "Coffee cup holder" and the answer is ZARF. The Wikipedia article on zarf explains that these holders originated in Turkey, perhaps with the rising popularity of coffee in the thirteenth century, and took their name from an Arabic word. While those holders were often highly ornamental, a web search suggests that the word applies now even to those cardboard sleeves that sometimes surround disposable coffee cups at Starbucks, Dunkin' Donuts, or McDonalds. It also names the mildly decorative foam rubber sleeves that keep your beer cold while promoting your favorite sports team.

I did not know.