The phrase "no spring chicken" is typically used to describe someone who is no longer young or in their prime. Antonyms for this phrase could include "young," "fresh," "vibrant," "energetic," "juvenile," "youthful," and "new." These words all convey a sense of youthfulness and vitality, portraying a positive image of someone who has not yet aged or lost their vigor. Conversely, "old," "tired," "aged," "worn," "weary," and "elderly" can all be considered synonyms for "no spring chicken." These words convey a sense of aging or weariness and are commonly used to describe someone who has lost some of their energy and vitality over time.