Definitions for "Half-Life, Biological"
time required for the body to eliminate 50 percent of a dose of any substance by the regular processes of elimination. This time is approximately the same for both stable isotopes and radionuclides of a particular element.
The time required for a living organism to eliminate, by natural processes, half the amount of a substance that has entered it.
time required for the body to eliminate one-half of an administered quantity of a radioactive chemical.