noun

1. a piece or division, esp. if flat and rectangular; specif.,
   1. a single division of a window, etc., consisting of a sheet of glass in a frame
   2. such a sheet of glass
2. a panel, as of a door, wall, etc.
3. any of the flat sides, or faces, as of a nut, bolt head, cut diamond, etc.
4. Philately
   1. a separate section of stamps, variously a quarter, half, or full sheet, as cut for sale
   2. a block of stamps sold in a booklet
      in full booklet pane

Etymology: ME pan < OFr < L pannus, piece of cloth < IE base *pan-, fabric > Gr pēnos, cloth, OE fana, banner