The Greek noun apostasion refers to a certificate of divorce or a bill of dismissal. It appears in Jesus' discussion of the Mosaic divorce law and is directly connected to the legal document that a husband could give his wife to officially dissolve their marriage. The word combines apo- (away from) and histemi (to stand/place).
Jesus' discussion of apostasion in Matthew 5:31-32 and 19:7-9 is central to New Testament ethics. He affirms that Moses permitted it 'because of the hardness of your hearts,' but that God's design from the beginning was one man and one woman, for life. Jesus radically tightens the divorce standard, protecting the dignity of women in a culture where divorce could be given for trivial reasons. Theologically, the marriage covenant reflects the covenantal relationship between God and His people — and the 'certificate of divorce' metaphor in Isaiah 50:1 and Jeremiah 3:8 describes God's discipline of Israel with the imagery of marital unfaithfulness.