surrogate mother

Definitions

General English

  • noun a woman who becomes pregnant and has a baby for a woman who is not able to do this herself,

Law

  • noun a woman who has a child by artificial insemination for a couple when the wife cannot become pregnant, with the intention of handing the child over to them when it is born

Medical

  • a person who takes the place of a natural mother for someone
http://www.dictionarycentral.com/definition/surrogate-mother.html