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]

The Collaborative International Dictionary of English v.0.48:

Panel \Pan"el\, v. t. [imp. & p. p. Paneledor Panelled; p.
   pr. & vb. n. Paneling or Panelling.]
   To form in or with panels; as, to panel a wainscot.
   [1913 Webster]

   Paneled back (Arch.), the paneled work covering the window
      back. See Window back.
      [1913 Webster]

WordNet (r) 3.0 (2006):

panel
    n 1: sheet that forms a distinct (usually flat and rectangular)
         section or component of something
    2: a committee appointed to judge a competition [syn: jury,
       panel]
    3: (law) a group of people summoned for jury service (from whom
       a jury will be chosen) [syn: panel, venire]
    4: a group of people gathered for a special purpose as to plan
       or discuss an issue or judge a contest etc
    5: a soft pad placed under a saddle
    6: a piece of cloth that is generally triangular or tapering;
       used in making garments or umbrellas or sails [syn: gore,
       panel]
    7: (computer science) a small temporary window in a graphical
       user interface that appears in order to request information
       from the user; after the information has been provided the
       user dismisses the box with `okay' or `cancel' [syn: dialog
       box, panel]
    8: electrical device consisting of a flat insulated surface that
       contains switches and dials and meters for controlling other
       electrical devices; "he checked the instrument panel";
       "suddenly the board lit up like a Christmas tree" [syn:
       control panel, instrument panel, control board,
       board, panel]
    v 1: decorate with panels; "panel the walls with wood"
    2: select from a list; "empanel prospective jurors" [syn:
       empanel, impanel, panel]