Answer :
the time required for half of something to undergo a process: such as. a : the time required for half of the atoms of a radioactive substance to become disintegrated.
Answer:
the time taken for the radioactivity of a specific isotope to fall to half its original value.
the time required for any specific property (e.g. the concentration of a substance in the body) to decrease by half.
Explanation:
I don't know if that's what your looking for