Supercilium is a stripe over the eye, running back from the bill.
https://en.wikipedia.org/wiki/Supercilium
The supercilium is a plumage feature found on the heads of some bird species. It is a stripe which runs from the base of the bird's beak above its eye, finishing somewhere towards the rear of the bird's head. Also known as an "eyebrow", it is distinct from the eyestripe, which is a line that runs across the lores, and continues behind the eye.