landgrave

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A man in medieval Germany who had jurisdiction over a particular territory.
• noun Used as the title for such a nobleman.

from The Century Dictionary.

• noun In Germany, in the middle ages, a graf or count to whom were intrusted special judicial functions, extending over a considerable territory; later, the title of certain German princes, some of whom were princes of the empire.

from the GNU version of the Collaborative International Dictionary of English.

• noun A German nobleman of a rank corresponding to that of an earl in England and of a count in France.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun rare specific nobiliary title ranking as count in certain feudal countships in the Holy Roman Empire, in present Germany.
• noun County nobleman in the British, privately held North American colony Carolina, ranking just below the proprietary (chartered equivalent of a royal vassal).

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a count who had jurisdiction over a large territory in medieval Germany