'excommunicator' originates from Latin, specifically the word 'excommunicare', where 'ex-' meant 'out of' and 'communis' meant 'common, shared'.

'excommunicator' changed from the Medieval Latin word 'excommunicatus' and Late Latin 'excommunicare', passed through Church Latin/Medieval usage and Middle English forms derived from the verb 'excommunicate', and eventually became the modern English agent noun 'excommunicator'.

Initially, the root meant 'to put out of the common (community)'; over time this developed into the modern sense relating to formal exclusion from a religious community and to the agent who performs or the person who receives that exclusion.