What is the term for the time it takes for half of a quantity of a radioactive substance to decay?

The term that specifically refers to the time it takes for half of a quantity of a radioactive substance to decay is "half-life." This concept is fundamental in the study of radioactive decay and nuclear physics. Half-life indicates that after one half-life, 50% of the original radioactive material has transformed into a different substance or isotope. This measurement is crucial for understanding the rate at which a radioactive substance will lose its radioactivity over time, as well as for practical applications in fields such as medicine, archaeology, and nuclear energy.

The terms “decay time,” “release time,” and “disintegration time” do not accurately capture the specific meaning associated with the concept of half-life. While they may imply some relation to decay, none of these options denote the precise quantity of time needed for half of the radioactive material to undergo decay, making "half-life" the correct term in this context.