udomitelj

1. (of animals) adopter
   Za ovo štene tražimo odgovornog udomitelja. — We're looking for a responsible adopter for this puppy.
   Mačka je konačno našla udomitelja. — The cat finally found someone to adopt her.
2. Croat. (of children) foster parent
   Dečak je odrastao kod udomitelja na selu. — The boy grew up with foster parents in the countryside.

For a foster parent, in Serbia: hranitelj (hraniteljska porodica); udomitelj in that sense is Croatian. In Serbia udomitelj is mostly used for pet adoption.