quin·qua·ge·nar·i·an I. \|kwinkwə̇jə̇|na(a)rēən, (|)kwin|kwäj-\adjective Etymology: Latin quinquagenarius of fifty, fifty years old (from quinquageni fifty each — from quinquaginta fifty — + -arius -ary) + English -an : fifty years old : characteristic of a person of such an age II. noun (-s) : a quinquagenarian person