Temporal Concept
half-life Audio
half·life
Subclass of:
Time
Definitions related to half-life:
  • (half life) The amount of time needed for a material to lose half of its physical, chemical, or biological activity.
    NCI
    U.S. National Cancer Institute, 2021
  • The time it takes for a substance (drug, radioactive nuclide, or other) to lose half of its pharmacologic, physiologic, or radiologic activity.
    NLM Medical Subject Headings
    U.S. National Library of Medicine, 2025
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