Past prime typically refers to something or someone who is no longer at their best. It can apply to objects that are worn or damaged, or people who are no longer as skilled or capable as they once were. Antonyms for past prime include young, fresh, new, current, vital, and thriving. These words all suggest something or someone that is still in their prime or is at the height of their abilities. They may convey a sense of energy, vitality, and potential, and may be used to describe new beginnings, life-changing experiences, or exciting opportunities.