"a cutting off or casting out from communication, deprivation of communion or the privileges of intercourse," specifically the formal exclusion of a person from religious communion and privileges, mid-15c., from Late Latin excommunicationem (nominative excommunicatio), noun of action from past-participle stem of excommunicare "put out of the community," in Church Latin "to expel from communion," from ex "out" (see ex-) + communicare "to share, communicate," related to communis "common" (see common (adj.)).