The Collaborative International Dictionary of English v.0.48:

Fusileer \Fu"sil*eer"\, Fusilier \Fu"sil*ier"\, n. [F. fusilier,
   fr. fusil.] (Mil.)
   (a) Formerly, a soldier armed with a fusil. Hence, in the
       plural:
   (b) A title now borne by some regiments and companies; as,
       "The Royal Fusiliers," etc.
       [1913 Webster]

WordNet (r) 3.0 (2006):

fusilier
    n 1: (formerly) a British infantryman armed with a light
         flintlock musket