long-livedness
long-lived
have one's whole life ahead of them
longeval
semperjuvenescent
veteration
beat the clock
shortgevity
progeroid
intergenerationally
intergeneration
four score and ten
obsoletion
outlive
aeonian
teens
eternal
eonian
longevously
senectitude
unceasing
geezerdom
outlast
perpetual
everlasting
ageless
from the dead
unending
youthless
immortality
nineteenish
nineteenness
aging
denarian
developed
senescent
ageing
emotional age
longevity
everlastingness
quarterlife
third age
twilight years
middle age
seniority
dateless
gerospan
persistent
seniorness
superannuation