The Collaborative International Dictionary of English v.0.48:
Brow \Brow\ (brou), n. [OE. browe, bruwe, AS. br[=u]; akin to
AS. br[=ae]w, bre['a]w, eyelid, OFries. br[=e], D. braauw,
Icel. br[=a], br[=u]n, OHG. pr[=a]wa, G. braue, OSlav.
br[u^]v[i^], Russ. brove, Ir. brai, Ir. & Gael. abhra, Armor.
abrant, Gr. 'ofry`s, Skr. bhr[=u]. Cf. Bray a bank,
1. The prominent ridge over the eye, with the hair that
covers it, forming an arch above the orbit.
And his arched brow, pulled o'er his eyes,
With solemn proof proclaims him wise. --Churchill.
2. The hair that covers the brow (ridge over the eyes); the
'T is not your inky brows, your brack silk hair.
3. The forehead; as, a feverish brow.
Beads of sweat have stood upon thy brow. --Shak.
4. The general air of the countenance.
To whom thus Satan with contemptuous brow. --Milton.
He told them with a masterly brow. --Milton.
5. The edge or projecting upper part of a steep place; as,
the brow of a precipice; the brow of a hill.
To bend the brow, To knit the brows, to frown; to scowl.