[1] : The Collaborative International Dictionary of English v.0.48

vadium \va"dium\, n. ll., from l. vas, vadis, bail. law
   pledge; security; bail. see mortgage.
   1913 webster

   vadium vivum ll. law, a living pledge, which exists
      where an estate is granted until a debt is paid out of its
      proceeds.
      1913 webster
see also:
mortgage vadium vivum 

[2] : Bouvier's Law Dictionary, Revised 6th Ed (1856)

vadium vivum, contracts. a species of security by which the borrower of a 
sum of money, made over his estate to the lender, until he had received that 
sum out of the issues and profits of the land; it was so called because 
neither the money nor the lands were lost, and were not left in lead pledge, 
but this was a living pledge, for the profits of the land were constantly 
paying off the debt. litt. sect. 206; 1 pow. on mort. 3; termes de la ley, 
h.t. 

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