What is Extravagantes?

Legal Definition
The term Extravagantes (from the Latin extra, outside; vagari, to wander) is applied to the canon law of the Roman Catholic Church, to designate some papal decretals not contained in certain canonical collections which possess a special authority. More precisely, they are not found in Gratian's 'Decretum or the three official collections of the Corpus Juris Canonici (the Decretals of Gregory IX, the Sixth Book of the Decretals, and the Clementines).
-- Wikipedia
Legal Definition
Canon law. This is the name given to the constitutions of the popes posterior to the Clementines; they are thus called quasi vagantes extra corpus juris, to express that they were out of the canonical law, which at first contained only the decrees of Gratian; afterwards the decretals of Gregory IX., the sexte of Boniface. VIII., the Clementines, and at last the extravagantes were added to it. There are the extravagantes of John XXII., and the common 'extravagantes.' The first contain twenty epistles, decretals or constitutions of that pope, divided under fifteen titles, without any subdivision into books. The others are epistles, decretals or constitutions of the popes who occupied the holy see, either before or after John XXII. they are divided into books like the decretals.
-- Bouviers Law Dictionary
Legal Definition
In canon law. Those decretal epistles which were published after the Clementines. They were so called because at first they were not digested or arranged with the other papal constitutions, but seemed to be, as it were, detached from the canon law They continued to be called by the same name when they wore afterwards inserted in the body of the canon law. The first extravagantes are those of Pope John XXII., successer of Clement V. The last collection was brought down to the year 1483, and was called the "Common Extravagantes," notwithstanding that they we:e likewise incorporated with the rest of the canon law. Enc. Lond.
-- Black's Law Dictionary