The Collaborative International Dictionary of English v.0.48:

Panel \Pan"el\, n. [Orig., a little piece; OF. panel, pannel, F.
   panneau, dim. of pan skirt, lappet, part or piece of a wall,
   side. See 2d Pane.]
   1. (Arch.) A sunken compartment with raised margins, molded
      or otherwise, as in ceilings, wainscotings, etc.
      [1913 Webster]

   2. (Law)
      (a) A piece of parchment or a schedule, containing the
          names of persons summoned as jurors by the sheriff;
          hence, more generally, the whole group of persons
          summoned on a particular day, from whom a jury is to
          be selected; also, the jury selected from that group.
          --Blackstone.
      (b) (Scots Law) A prisoner arraigned for trial at the bar
          of a criminal court. --Burrill.
          [1913 Webster]

   3. Hence: Any group of persons selected to judge a contest,
      conduct a discussion, serve as advisers, or participate in
      any group activity in which they will provide information
      or make judgments.
      [PJC]

   4. Formerly, a piece of cloth serving as a saddle; hence, a
      soft pad beneath a saddletree to prevent chafing.
      [1913 Webster]

   5. (Joinery) A board having its edges inserted in the groove
      of a surrounding frame; as, the panel of a door.
      [1913 Webster]

   6. (Masonry) One of the faces of a hewn stone. --Gwilt.
      [1913 Webster]

   7. (Painting) A slab or plank of wood upon which, instead of
      canvas, a picture is painted.
      [1913 Webster]

   8. (Mining)
      (a) A heap of dressed ore.
      (b) One of the districts divided by pillars of extra size,
          into which a mine is laid off in one system of
          extracting coal.
          [1913 Webster]

   9. (Dressmaking) A plain strip or band, as of velvet or
      plush, placed at intervals lengthwise on the skirt of a
      dress, for ornament.
      [1913 Webster]

   10. A portion of a framed structure between adjacent posts or
       struts, as in a bridge truss.
       [1913 Webster]

   11. (A["e]ronautics) A segment of an a["e]roplane wing. In a
       biplane the outer panel extends from the wing tip to the
       next row of posts, and is trussed by oblique stay wires.
       [Webster 1913 Suppl.]

   Panel game, a method of stealing money in a panel house.

   Panel house, a house of prostitution in which the rooms
      have secret entrances to facilitate theft from customers
      by accomplices of the inmates.

   Panel saw, handsaw with fine teeth, -- used for cutting out
      panels, etc.

   Panel thief, one who robs in a panel house.
      [1913 Webster]