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half-life

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English

Noun

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Singular
half-life

Plural
half-lives

half-life (half-lives)
  1. (physics) The time required for half of the nuclei in a sample of a specific isotope to undergo radioactive decay.
  2. (chemistry) In a chemical reaction, the time required for the concentration of a reactant to fall from a chosen value to half that value.
  3. (medicine) The time it takes for a substance (drug, radioactive nuclide, or other) to lose half of its pharmacologic, physiologic, or radiologic activity. Year introduced in w:MeSH: 1974(1971)
  4. (culture) The time it takes for an idea or a fashion to lose half of its influential power. "Most books of scholarship have surprisingly short intellectual half-lives during which they make a difference" (Robert Ackerman, 1991. Introduction to Jane Ellen Harrison's Prolegomena to the Study of Greek Religion (1903).)

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