Source : Webster's Revised Unabridged Dictionary (1913)

Decretal \De*cre"tal\, a. [L. decretalis, fr. decretum. See
   {Decree}.]
   Appertaining to a decree; containing a decree; as, a decretal
   epistle. --Ayliffe.

Decretal \De*cre"tal\, n. [LL. decretale, neut. of L.
   decretalis. See {Decretal}, a.]
   1. (R. C. Ch.) An authoritative order or decree; especially,
      a letter of the pope, determining some point or question
      in ecclesiastical law. The decretals form the second part
      of the canon law.

   2. (Canon Law) The collection of ecclesiastical decrees and
      decisions made, by order of Gregory IX., in 1234, by St.
      Raymond of Pennafort.