VADIUM MORTUUM, contracts. A mortgage or dead-pledge; it is a security given by the borrower of a sum of money, by which he grants to the lender an estate in fee, on condition that if the money be not repaid at the time appointed, the estate so put in pledge shall continue to the lender as dead or gone from the mortgagor. 2 Bl. Com. 257; 1 Pow. Mortg. 4.