eyebrow

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The bony ridge extending over the eye.
2. n. The arch of short hairs covering this ridge.

Century Dictionary and Cyclopedia

1. n. The brow, or prominence of parts, over the eye; a prominent superorbital formation; a superciliary ridge or shield. In man the bony basis of the eyebrow is the frontal bone along the upper margin of the orbits, made somewhat more prominent by the development of the frontal sinuses or hollows within the bone. (See cut under skull.) The projection, however, is slight in comparison with the beetling superorbital ridges of many animals, as the gorilla. In birds, and in many reptiles and fishes, the eyebrow is a separate formation of a bone, or chain of bones, along the upper edge of the orbit, whose nature is that of the lacrymal bone. These are known as superorbitals, or superorbital bones or ossicles. (See cut under Lepidosiren.) One such bone forms the movable superciliary shield of some birds, as eagles, projecting like the eaves of a roof over the eye. The eyebrows include the soft parts, as flesh and skin, which cover the bone. See supercilium.
2. n. A fringe of hairs growing on the brow of the eye; the supercilia. See cut under eye.
3. n. In ornithology, a superciliary streak of color.
4. n. In architecture, a molding over a window; a window-cap: in American usage, a light dormer without vertical sides sot in a roof.

Wiktionary

1. n. The hair that grows over the bone ridge above the eye socket.
2. n. construction A dormer, usually of small size, whose roof line over the upright face is typically an arched curve, turning into a reverse curve to meet the horizontal line at either end.

GNU Webster's 1913

1. n. The brow or hairy arch above the eye.

WordNet 3.0

1. n. the arch of hair above each eye