a. The superciliary ridge over the eyes.
b. The eyebrow.
c. The forehead.
2. A facial expression; countenance: "Speak you this with a sad brow?" (Shakespeare).
3. The projecting upper edge of a steep place: the brow of a hill.
[Middle English, from Old English brū; see bhrū- in the Appendix of Indo-European roots.]
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