boomeranger
n. An adult child who returns home to live with his or her baby-boomer parents.
Examples
2001
Though many students only stay for a few months, others linger at home even after they are on their feet financially. They are attracted by a room of their own, disposable income, and eager-to-help baby-boomer parents who are welcoming their "boomerangers" — as they are being called — back to the nest.
—Kim Campbell, “More graduates opt to live with mom and dad,” The Christian Science Monitor, July 09, 2001
1987 (earliest)
"Well, the dog hadn't died, but when my children were finally grown and out of the house, my wife and I had a pretty blissful situation." That was until last August, when Jones's 25-year-old son moved back home. He was in rough shape financially, having quit a selling job on the West Coast. … Jones laughs again. "Thomas Wolfe is wrong. You can come home again, if not spiritually, at least physically." Sociologists and marketing experts call them "boomerangers", adult children who have returned to the family nest.
—Mary Amoroso, “Boomerangers,” The Record, November 29, 1987