middle-agerorig.U.S. [f. middle age n. + -er1.] A middle-aged person. 1949Labor & Nation Jan.–Feb. 7 Not every youngster or middle-ager..is a double dealer.1956N.Y. Times Mag. 29 July 5 (heading) America's unknown middle-agers.1962Punch 12 Sept. 392/3 A tough competent middleager.