archiepiscopal
adjective
ar·chi·epis·co·pal ˌär-kē-ə-ˈpi-skə-pəl 
: of or relating to an archbishop
archiepiscopally
ˌär-kē-ə-ˈpi-skə-p(ə-)lē
adverb 
Word History
Etymology
Medieval Latin archiepiscopalis, from Late Latin archiepiscopus archbishop — more at archbishop
First Known Use
1611, in the meaning defined above