subtenant

from The Collaborative International Dictionary of English v.0.48
Subtenant \Sub*ten"ant\, n. (Law)
   One who rents a tenement, or land, etc., of one who is also a
   tenant; an undertenant.
   [1913 Webster]
    
from Bouvier's Law Dictionary, Revised 6th Ed (1856)
SUB-TENANT. The same as under-tenant. See Under-leaser; Under-tenant, and 1 
Bell's Com. 76. 
    

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