a person who is knowledgeable on the subject of the Decretals or the papal edicts that make up part of canon law
decretist in American English
(dɪˈkritɪst)
noun(in medieval universities)
1.
a student in the faculty of law
2.
a student of the Decretals; expert in the canon law
Word origin
[1350–1400; ‹ ML dēcrētista, equiv. to L dēcrēt(um) decree + -ista-ist]This word is first recorded in the period 1350–1400. Other words that entered Englishat around the same time include: drag, flash, kick, negative, screen-ist is a suffix of nouns, often corresponding to verbs ending in -ize or nouns ending in -ism, that denote a person who practices or is concerned with something, or holds certainprinciples, doctrines, etc. Other words that use the affix -ist include: Thomist, apologist, dramatist, novelist, realist