Definition of Feudorum liber
The Books of Feuds. A compilation of feudal law, prepared by order of the emperor Frederick I, and published at Milan in 1170. It comprised five books, of which only the first two are now extant with fragmentary portions of the others, printed at the end of modern editions of the Corpus Juris Civilis.
That's the definition of Feudorum liber in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.