You’re likely more familiar with the phrasal verb form of “festoon,” “to be festooned with,” meaning a place or thing is decorated with streamers, garlands, and other hanging swaths of material. This phrase developed from the noun “festoon,” which is the word for the actual materials. Festoons are traditionally chains of flowers or greenery that are draped in a curve as a decoration. The word comes from the Latin “festa,” meaning “feast,” where they originally served as decoration. They were adopted as an architectural decoration as well, so you’ll see festoons carved into marble and other stonework.