to deprive (somebody) officially of the rights of church membership
to exclude (somebody) from fellowship of a group or community
excommunication /-ʹkaysh(ə)n/ noun
excommunicative /-kətiv/ adj
excommunicator noun
excommunicatory /-kət(ə)ri/ adj
[Middle English excommunicaten from late Latin excommunicatus, past part. of excommunicare, from ex-1 + communicare: see communicate]