eyebrow

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The bony ridge extending over the eye.
• noun The arch of short hairs covering this ridge.
• noun A small, arched dormer that projects only slightly from the roof.

from The Century Dictionary.

• noun In architecture, a molding over a window; a window-cap: in American usage, a light dormer without vertical sides sot in a roof.
• noun The brow, or prominence of parts, over the eye; a prominent superorbital formation; a superciliary ridge or shield.
• noun A fringe of hairs growing on the brow of the eye; the supercilia. See cut under eye.
• noun In ornithology, a superciliary streak of color.

from the GNU version of the Collaborative International Dictionary of English.

• noun The brow or hairy arch above the eye.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The hair that grows over the bone ridge above the eye socket.
• noun 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.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the arch of hair above each eye