The Collaborative International Dictionary of English v.0.48:

Pennon \Pen"non\, n. [Cf. Pinion.]
   A wing; a pinion. --Milton.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pennon \Pen"non\, n. [See Pennant.]
   A pennant; a flag or streamer. --Longfellow.
   [1913 Webster] Pennoncel

WordNet (r) 3.0 (2006):

pennon
    n 1: a long flag; often tapering [syn: pennant, pennon,
         streamer, waft]
    2: wing of a bird [syn: pennon, pinion]