Foster-mother and Foster parent

Foster-mother noun - A woman who is a foster parent and raises another's child.

Foster parent and foster-mother are semantically related. In some cases you can use "Foster parent" instead a noun phrase "Foster-mother".

Foster parent noun - A person who acts as parent and guardian for a child in place of the child's natural parents but without legally adopting the child.

Foster-mother and foster parent are semantically related. Sometimes you can replace phrase "Foster-mother" with "Foster parent", this phrases are similar.