Source : Webster's Revised Unabridged Dictionary (1913)

Subrogate \Sub"ro*gate\, v. t. [L. subrogatus, p. p. of
   subrogare. See {Surrogate}.]
   To put in the place of another; to substitute. --Barrow.

Source : WordNet®

subrogate
     v : substitue one creditor for another, as in the case where an
         insurance company sues the person who caused an accident
         for the insured