A nonagenarian is a person in their nineties.
the age of 90 or between 90 and 100 years old
a nonagenarian is anyone between the ages of 90 and 100.
'Nonagenarian' is the correct spelling (not 'Nonogenarian').
octogenarian Someone who is between 80 and 89 years old is called an octogenarian. If that's not what you're looking for, senior, older person, or some similar term may work.
The author LeRoy Newton Mills is known for writing books on the history and practice of martial arts, particularly karate and kung fu. His works often focus on the techniques, philosophies, and traditions of these martial arts.