"On the ball" is a phrase that means to be alert, competent and quick to understand and respond to a situation. Some synonyms for "on the ball" are "sharp", "attentive", "focused", "alert", "quick-witted", "astute", "observant" and "knowledgeable". These words convey a sense of someone who is adept at making quick and accurate decisions, and is always ready to tackle any challenges that come their way. Being "on the ball" is a coveted trait in many professions, including business, sports, teaching, and law enforcement. With these synonyms, you can expand your vocabulary and better describe people who are always on top of their game.