The word "became better" is synonymous with improvement, progress, and advancement. However, it also has antonyms that describe the opposite, such as deterioration, decline, and regression. When something is deteriorating, it means it's getting worse or breaking down. The word decline connotes a gradual decrease or downward trend in quality, quantity or strength. The word regression implies that things are reverting to an earlier state, losing ground or declining in performance. These antonyms are polar opposite of becoming better and can bring about negative outcomes if not adequately handled.