The Collaborative International Dictionary of English v.0.48:

Beetle-browed \Bee"tle-browed`\, a. [OE. bitelbrowed; cf. OE.
   bitel, adj., sharp, projecting, n., a beetle. See Beetle an
   insect.]
   Having prominent, overhanging brows; hence, lowering or
   sullen.
   [1913 Webster]

   Note: The earlier meaning was, "Having bushy or overhanging
         eyebrows."
         [1913 Webster]