The Collaborative International Dictionary of English v.0.48:

Panache \Pa*nache"\, n. [F., fr. L. penna a feather. See Pen a
   feather.]
   1. A plume or bunch of feathers, esp. such a bunch worn on
      the helmet; any military plume, or ornamental group of
      feathers.
      [1913 Webster]

            A panache of variegated plumes.       --Prescott.
      [1913 Webster]

   2. A pleasingly flamboyant style or manner; flair[4]; verve.
      [PJC] Panada

WordNet (r) 3.0 (2006):

panache
    n 1: distinctive and stylish elegance; "he wooed her with the
         confident dash of a cavalry officer" [syn: dash, elan,
         flair, panache, style]
    2: a feathered plume on a helmet