'excommunicate' originates from Latin, specifically the Late Latin word 'excommunicare', where 'ex-' meant 'out of' and 'communicare' meant 'to share, to make common (from communis "common").

'excommunicare' passed into Medieval/Low Latin and then into Middle English (forms like 'excommunicaten'), eventually becoming the modern English 'excommunicate'.

Initially it meant 'to deprive of communion or shared participation (in the church)', and over time it evolved into the broader modern sense of 'to officially exclude or bar from membership or participation'.