Marquess is a alternative form of marquis.

Marquess is a coordinate term of marquis.

As nouns the difference between marquis and marquess

is that marquis is 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 patent while marquess is a title of nobility, ranking beneath a duke and above an earl.