The Collaborative International Dictionary of English v.0.48:

Feather-edge \Feath"er-edge`\, n.
   1. (Zool.) The thin, new growth around the edge of a shell,
      of an oyster.
      [1913 Webster]

   2. Any thin, as on a board or a razor.
      [1913 Webster]

WordNet (r) 3.0 (2006):

featheredge
    n 1: a thin tapering edge

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "featheredge":
   bank, board, border, bordure, brim, brink, brow, coast,
   cutting edge, edge, edge tool, flange, frame, fringe, hem,
   knife-edge, labellum, labium, labrum, ledge, limb, limbus, lip,
   list, marge, margin, ragged edge, razor-edge, rim, selvage, shore,
   side, sideline, skirt, verge, weapon