Pertaining to a decree.

(Roman Catholicism) A papal decree, particularly one derived from an ecclesiastical letter. / (now rare) Any decree or pronounced instruction.

plural of decretal

(historical) A member of a 13th-century school of interpretation of canon law that emphasized the decretals (letters issued by the Popes on matters of church discipline) in preference to the Decretum Gratiani (1141), which their rivals, the decretists, favoured.

(historical) The beliefs of the decretalists.

plural of decretalist