Definition of "marquis"

A nobleman in England, France, and Germany, of a rank next below that of duke, but above a count. Originally, the marquis was an officer whose duty was to guard the marches or frontiers of the kingdom. The office has ceased, and the name is now a mere title conferred by letters patent or letters close.  examples

Any of various nymphalid butterflies of the Asian genus Bassarona (or Euthalia).  examples