My day started as Shu tripped over the dogs leash and fell head first into a window, which fortunately did not break. However, the skin on his forehead, right above his eye, did. So that meant a trip to the ER for some stitches. "So the cut is near my supercilium, right?", he said. The doctor said, "What?" Sure enough, and I didn't know it, supercilious is derived from the Latin word meaning "hair of the eyebrow." That's also where supercilious derives.
The OED says supercilium is rare, so I assume none of you use it?