Foster-father and Father surrogate

Foster-father noun - A man who is a foster parent.

Father surrogate and foster-father are semantically related. In some cases you can use "Father surrogate" instead a noun phrase "Foster-father".

Father surrogate noun - A man who takes over all the functions of the real father.

Foster-father and father surrogate are semantically related. Sometimes you can replace phrase "Foster-father" with "Father surrogate", this phrases are similar.