Thomas Laird carried out the catalogue of abuse over an 18-year period at addresses in Glasgow, Dunbartonshire and Lanarkshire.
One woman told the High Court in Glasgow that Laird had groomed her sister from the age of 11. She sobbed as she told how the 38-year-old supermarket worker had produced a knife and threatened to rape her after she found out her sister was pregnant by him. Laird was brought to justice after one of his victims contacted the police domestic abuse taskforce.
Sentencing was deferred until later this month at the High Court in Edinburgh.