From Longman Dictionary of Contemporary Englishdukedomduke‧dom /ˈdjuːkdəm $ ˈduːk-/ noun [countable] 1 PGOthe rank of a duke2 PGOAREAthe land and property belonging to a duke SYN duchy
Examples from the Corpus
dukedom• John Howard received his dukedom, supported Richard against rebels later the same year, and died with him at Bosworth. 