The word "tenacious" means holding firmly to something, whether it is an idea, a belief, or a goal. It implies a strong determination and persistence in pursuing or maintaining something. This word is often used to describe someone who does not easily give up or let go of their objectives or principles. "Tentative" means uncertain or hesitant, which is the opposite of being tenacious. "Determined" is a synonym of tenacious, as it also conveys a strong resolve and perseverance. "Weak" is the opposite of tenacious, suggesting a lack of strength or determination.