The word "in-aptitude" refers to a lack of skill, talent, or ability in a particular area. Some of the antonyms for in-aptitude include competence, expertise, proficiency, mastery, dexterity, and skillfulness. These words indicate a high level of skill or ability in a specific field or activity. Other antonyms for in-aptitude include talent, gift, and aptitude, all of which describe natural ability or inclination towards a particular subject. These antonyms highlight the contrast between lacking ability and possessing it, revealing the importance of honing one's skills and talents to succeed in various domains of life.