Biological age
\ˌbaɪəˈlɑʤɪkəl\ \eɪʤ\
The measure of how old a person seems, allowing for the fact the aging of the body takes place at different rates for different people depending on genetic and environmental influences.
Biological age differs from chronological age in that it takes account of the effect of genetic and environmental factors on an individual’s lifespan. Experts have not yet found a satisfactory measure by which to determine a person’s biological age independently from their chronological age, although various models take account of factors such as health, medical conditions, lifestyle, etc, to estimate biological age (and there are even apps that attempt to measure this using a selfie!).