1. plural of half-life; the time required for a radioactive substance to decay to half its original amount
Usage: physics/chemistry term; commonly used in scientific contexts
2. plural of half-life; the time it takes for a substance or effect to reduce to half its initial value or strength
Usage: general usage; can apply to medications, pollutants, or other contexts

Examples

• The halflives of different isotopes vary dramatically, from fractions of a second to billions of years.
• Carbon-14 has a half-life of about 5,730 years, making it useful for dating archaeological artifacts.
• Understanding the halflives of medications helps doctors determine proper dosing schedules.
• The halflives of pollutants in the environment determine how long they persist in ecosystems.
• Scientists measure halflives to predict how quickly radioactive materials will become safe.