the.com/pelmet

means A pelmet is a narrow decorative band of fabric or board fitted above a window to conceal curtain rails, hooks, and other unglamorous hardware.

from The word entered English from French 'palmette,' a small ornamental palm-leaf shape used in classical decoration, which itself traces back to Greek 'palmē' for palm tree. How a leaf motif became the word for a curtain-topper isn't fully documented, but the likely path is that the ornamental border designs — often palm-leaf shaped — lent their name to the whole decorative strip, even once the actual leaf pattern was long gone.