The opposite of lacking confidence is having confidence. Confidence is defined as the belief in oneself and one's abilities. There are several antonyms for the phrase "lack confidence," including assurance, self-assurance, self-confidence, and poise. When an individual possesses self-assurance or poise, they exude a sense of certainty in their abilities and are unafraid to take risks. Self-confidence also allows an individual to trust their inner voice and intuition, enabling them to make sound decisions. When one has assurance, they don't hesitate to take charge of a situation and exhibit strong leadership qualities. In short, lacking confidence can be debilitating, whereas possessing confidence can help one achieve their goals and be successful in life.