gam·ma (gămˈə)

1. Symbol γ The third letter of the Greek alphabet.
2. The third item in a series or system of classification.
3. The third position from a designated carbon atom in an organic molecule at which an atom or a radical may be substituted.
4. A unit of magnetic field strength equal to one hundred thousandth (10⁵) of an oersted.
5. A unit of mass equal to one millionth (10⁶) of a gram.

1. Relating to or being the atom or radical group that is in the third position relative to the functional group of atoms in an organic molecule.
2. Relating to or characterizing a polypeptide chain that is one of five types of heavy chains that may be present in immunoglobins.