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half-life

Syllabification: half-life

Definition of half-life in English:

noun

1The time taken for the radioactivity of a specified isotope to fall to half its original value.
Example sentences
  • The small, lead-shielded canisters contain pellets or a fine powder of caesium 137, which emits powerful gamma radiation with a half-life of 30 years.
  • Tritium is radioactive, with a half-life of 12.26 years.
  • The FDA recommends keeping a fourteen-day supply on hand; radioactive iodine has a half-life of eight days.
1.1The time required for any specified property (e.g., the concentration of a substance in the body) to decrease by half.
Example sentences
  • Frova may represent an important advancement in the treatment of migraine headache as no other currently marketed treatment has a half-life of more than six hours.
  • Prealbumin, also known as transthyretin, has a half-life of only 1 to 2 days.
  • At age 18, caffeine has a half-life of 4.5 hours, which increases with age.

Definition of half-life in:

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