RIVERTON, Kan. — The Keenagers, a not-for-profit senior citizens’ chorus based in Riverton, Kansas, is looking for new members, aged 50 and older, from across the Four States. But what exactly is a “keenager?” The term is used to describe those 65 years and older, who are semi-retired and still maintain an active lifestyle at home and within their communities. Some say they act like teenagers, but with more experience.