age
Priority is given to students under 20 (years of age)
She is four years older than I;  She is four years senior to me;  She is my senior by four years
He is four years younger than I;  He is four years junior to me;  He is my junior by four years
I am his age
How old do you think I am ?
I'm too old for this job
This is the classroom for children between 10 and 12 years of age/between the ages of 10 and 12/from 10 to 12 years of age
That director is in his fifties
Quinquagenarian/Sexagenarian/Septuagenarian/Octogenarian/Nonagenarian/Centenarian