half-life
التعريفات والمعاني
== English ==
=== Etymology ===
From half- + life.
=== Pronunciation ===
(US) IPA(key): /ˈhæfˌlaɪf/
=== Noun ===
half-life (plural half-lives)
(nuclear physics) The time required for half the nuclei in a sample of an isotope to undergo radioactive decay.
(physical chemistry) In a chemical reaction, the time required for the concentration of a reactant to fall from a chosen value to half that value.
(medicine, pharmacology) The time it takes for a substance (drug, radioactive nuclide, or other) to lose half of its pharmacological, physiologic, or radiological activity.
The amount of time it takes for an idea or a fashion to lose half of its influential power.
1991, Robert Ackerman, Introduction to Jane Ellen Harrison's Prolegomena to the Study of Greek Religion (1903)
Most books of scholarship have surprisingly short intellectual half-lives during which they make a difference"
==== Translations ====
==== See also ====
radioactivity