How old is old? World Health Organization (WHO) had declared that 65 years is still considered young.
Before, based on the Friendly Societies Act (1875) in Britain, old was defined by age of 50. The UN has not adopted a standard criterion but lately 60 years old was referred as the border age to the word ‘old’. However the health organization had done a new research recently, according to average health quality and life expectancy and defined a new criterion that divides human age as follows:
0 to 17 years old: underage
18 to 65 years old: youth or young people
66 to 79 years old: middle-aged
80 to 99 years old: elderly or senior
100+ years old: long-lived elderly