noun

• A protein present in fetal serum; specifically (more fully "alpha-fetoprotein") a glycoprotein which is the predominant serum protein of the fetus and can also be detected in amniotic fluid and maternal blood, in which an elevated level is associated ​with certain congenital abnormalities of the fetus, especially spina bifida and anencephaly; abbreviated AFP.

  Alpha-fetoprotein is also an oncofetal antigen, found at an elevated level in the blood of persons with certain cancers and other diseases, especially of the liver.