The geologic age of a fossil organism, rock, or geologic feature or event given in units of time, usually years. Commonly used as a syn. of isotopic age or radiometric age, but may also refer to ages obtained from tree rings, varves, etc. Term is now in disfavor as it implies a certainty or exactness that may not be possible by present dating methods; i.e., two absolute ages for the same pluton may disagree by hundreds of millions of years.