What is "hrabischitz"

The House of Hrabischitz was an important North Bohemian aristocratic family, that was also called the lords of Osek or of Osek and Riesenburg (Czech: z Oseka) but were also named von Riesenburg after their castle, the Riesenburg. The history of the family goes back to the 11th century. The family rapidly fell on hard times in the 15th century and died out in the early 16th century. <!--