[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, contracts. a pledge, or surety. 

Vadium >> V Words
Vadium, definition of term: Vadium
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