Half-life

Quick meaning: Half-life is a noun meaning (nuclear physics) The time required for half the nuclei in a sample of an isotope to undergo radioactive decay.

Meaning

(nuclear physics) The time required for half the nuclei in a sample of an isotope to undergo radioactive decay.

More Meanings

1. The amount of time it takes for an idea or a fashion to lose half of its influential power.
2. (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.
3. (medicine, pharmacology) The time it takes for a substance (drug, radioactive nuclide, or other) to lose half of its pharmacological, physiologic, or radiological activity.

Example Sentences

Most books of scholarship have surprisingly short intellectual half-lives during which they make a difference"

For nonporous surfaces such as steel, in a dark and low-humidity environment, the CCP virus has an 18-hour half-life—the time required for it to decrease by half , according to the researchers' findings.

O₂^(•−) and OH^• are highly unstable (half-life at the level of microseconds and nanoseconds, respectively) and cannot cross membrane, while H₂O₂, though not a free radical but a ROS, is relatively stable (half-life around 1 ms) (Møller et al. 2007) and can cross membranes through aquaporins.

"The guy that just left—what's he got in his lungs?" / "Well, I'm not very sure. But the two best candidates are uranium-233 and plutonium-239, one or both." / "They're in his bones too, aren't they?" / "Yeah, they're both boneseekers. And they've got half-lives of one hundred sixty-two thousand and twenty-four thousand years respectively. So they stay hot for a long time."

Word Forms

• half-lives

Related Words

Related dictionary entries include average, period, substance, half-time, time constant, halvation.

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