juniorEnglishOxford American Thesaurusjunior adjective 1 the junior members of the family: younger, youngest. ▷antonyms senior, older. 2 Virginia's junior senator | part of my function is to supervise those junior to me: low-ranking, lower-ranking, subordinate, sub-, lesser, lower, minor, secondary, inferior; beneath, under. ▷antonyms higher-ranking, senior. 3 John White Junior: the Younger; British minor; North American II. ▷antonyms Senior.