The Greek adjective aposunagogos means expelled from or excluded from the synagogue. It is a compound of apo- (away from) and synagoge (synagogue/assembly), denoting formal excommunication from the Jewish religious community. This was a severe social and religious penalty.
Aposunagogos appears only three times in the New Testament, all in John's Gospel, and all in the context of the growing conflict between Jewish Christians and the synagogue establishment. The parents of the man born blind feared being made aposunagogos (John 9:22) and refused to testify about Jesus. Jesus warns His disciples that they will be put out of the synagogue (John 16:2). The word reflects the painful social reality of early Jewish Christianity — choosing to follow Jesus meant potential loss of community, family ties, and religious identity. Theologically, it foreshadows the ultimate separation of synagogue and church and the cost of discipleship.