adj appertaining to a decree; containing a decree; as, a decretal epistle.
2. decretal ·adj the collection of ecclesiastical decrees and decisions made, by order of gregory ix., in 1234, by st. raymond of pennafort.
3. decretal ·adj 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.