landgrave(n = noun.person) - a count who had jurisdiction over a large territory in medieval Germany;
is a kind of count

   A German nobleman of a rank corresponding to that of an earl in England and of a count in France. [1913 Webster]
" The title was first adopted by some German counts in the twelfth century, to distinguish themselves from the inferior counts under their jurisdiction. Three of them were princes of the empire." [1913 Webster]

landgrave, n. (fem. landgravine) hist.
1 a count having jurisdiction over a territory.
2 the title of certain German princes.

Derivative:
landgraviate n.

Etymology:
MLG landgrave, MHG lantgrave (as LAND, G Graf COUNT(2))