sexagenarian

nouns

someone whose age is in the sixties
is a type of (narrower)
an elderly person

adjectives

being from 60 to 69 years old
"the sexagenarian population is growing"
is similar to
(used especially of persons) having lived for a relatively long time or attained a specific age
"his mother is very old"; "a ripe old age"; "how old are you?"