superager noun [C]
UK /suː.pər.ˈeɪ.dʒəʳ/ US /suː.pɚ.ˈeɪ.dʒɚ/
someone over the age of 65 whose memory and thinking skills are similar to those of someone in their 20s

Her advice is based on a study of “superagers”, individuals 65 years or older, whose cognitive skills are as acute as the average 25-year-old. Barrett believes that what sets superagers apart is their ability to use the unpleasant feelings they experience when challenging themselves as a signal to keep going, rather than as a warning to stop and rest.
[www.telegraph.co.uk, 10 July 2018]

silver striver noun [C]
UK /sɪl.və.ˈstraɪvəʳ/ US /sɪl.vɚ.ˈstraɪvɚ/
someone who continues to work after they have passed the typical retirement age

Peter Stanway, 72, is helping to design a block of flats overlooking the zebra crossing that appears on the cover of the Beatles’ Abbey Road. Although he started drawing his state pension at 70, he still works between 30 and 50 hours a week and has no plans to retire until he is 80. Stanway … is part of a new demographic — the silver strivers. These are the baby boomers who, when they reached state pension age, simply kept on working.
[Sunday Times, 11 March 2018]

grey tsunami noun [S]
/greɪ.tsuːˈnɑː.mi/
the high number of elderly people in the world in the 21st century, caused by people living longer and by the “baby boomer” generation now reaching old age

We have been warned, for years, of a so-called “grey tsunami” that is about to crash into our society. … This represents a challenge for hospitals, nursing homes and families. And it comes with significant costs. Describing this demographic shift as a “grey tsunami” — with its terrifying image of a monstrous wave poised to break over our heads — is striking and urgent.
[www.cba.ca, 15 October 2017]

About new words