Black’s Law Dictionary, 1st Edition, page 504:
A process in chancery by which all further right existing in a mort gagor to redeem the estate is defeated and lost to him, and the estate becomes the absolute property of the mortgagee; being applicable when the mortgagor has forfeited his estate by non-payment of the money due on the mortgage at the time appointed, but still retains the equity of redemption. 2 Washh. Real Prop. 237.
The term is also loosely applied to any of the various methods, statutory or otherwise. known in different jurisdictions, of enforcing payment of the debt secured by a mortgage, by taking and selling the mortgaged estate. Foreclosure is also applied to proceedings founded upon some other liens thus there are proceedings to foreclose a mechanic’s lien.