step-father

from The Collaborative International Dictionary of English v.0.48
Stepfather \Step"fa`ther\, n. [AS. ste['o]pfaeder.]
   The husband of one's mother by a subsequent marriage.
   [1913 Webster]
    
from Bouvier's Law Dictionary, Revised 6th Ed (1856)
STEP-FATHER. In Latin vitricus, is the husband of one's mother who is not 
the father of the person spoken of. 
    

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