The Collaborative International Dictionary of English v.0.48:

Hussar \Hus*sar"\, n. [Hung. husz['a]r, from husz twenty,
   because under King Matthais I., in the fifteenth century,
   every twenty houses were to furnish one horse soldier; cf. G.
   husar, F. houssard, hussard, from the same source.] (Mil.)
   Originally, one of the national cavalry of Hungary and
   Croatia; now, one of the light cavalry of European armies.
   [1913 Webster]

WordNet (r) 3.0 (2006):

hussar
    n 1: a member of a European light cavalry unit; renowned for
         elegant dress