Meaning of half-life

half-life

Pronunciation: (haf'līf", häf'-), [key]
— pl. -lives
  1. the time required for one half the atoms of a given amount of a radioactive substance to disintegrate.
  2. the time required for the activity of a substance taken into the body to lose one half its initial effectiveness.
  3. a brief period during which something flourishes before dying out.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
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