Oxford Dictionary English the third age nounnoun BrE BrE//ðə ˌθɜːd ˈeɪdʒ// ; NAmE NAmE//ðə ˌθɜːrd ˈeɪdʒ// [singular] (British English) Add to my wordlistjump to other resultsthe period of your life between middle age and old age, when you are still activeCheck pronunciation: the third age oxfordlearnersdictionaries.com