The Collaborative International Dictionary of English v.0.48:

Knop \Knop\ (n[o^]p), n. [OE. knop, knoppe; cf. D. knop, knoop,
   G. knopf, Dan. knap, knop, Sw. knapp, knopp, button, bud,
   Icel. knappr, and E. knap, n. Cf. Knap, Knob.]
   1. A knob; a bud; a bunch; a button.
      [1913 Webster]

            Four bowls made like unto almonds, with their knops
            and their flowers.                    --Ex. xxv. 21.
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   2. (Arch.) Any boldly projecting sculptured ornament; esp.,
      the ornamental termination of a pinnacle, and then
      synonymous with finial; -- called also knob, and
      knosp.
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   Knop sedge (Bot.), the bur reed (Sparganium); -- so
      called from its globular clusters of seed vessels.
      --Prior.
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The Collaborative International Dictionary of English v.0.48:

Finial \Fin"i*al\, n. [L. finire to finish, end. See Finish.]
   (Arch.)
   The knot or bunch of foliage, or foliated ornament, that
   forms the upper extremity of a pinnacle in Gothic
   architecture; sometimes, the pinnacle itself.
   [1913 Webster]

WordNet (r) 3.0 (2006):

finial
    n 1: an ornament at the top of a spire or gable; usually a
         foliated fleur-de-lis