carbon-14 dating

[noun]

A technique used to determine the age of an organic object by measuring the amount of the radioactive isotope ¹⁴C in the object. While an organism is alive, it maintains a constant amount of ¹⁴C, but once an organism dies, the ¹⁴C that was present at the time of death decays. Also called ¹⁴C-dating or radiocarbon dating.