on in yearsSee: ALONG IN YEARS.
{v. phr.} To age; grow old.
My father is getting along in years; he will be ninety on his next birthday.{adj. phr.} Elderly; growing old.
As Grandfather got on in years, he became quiet and thoughtful. Our dog isn 't very playful because it is getting on in years. [TahlilGaran] English Idioms Dictionary ▲