In-effective is a term used to describe something that is not able to produce the desired outcome. Antonyms for in-effective include effective, efficient, productive, successful, powerful, potent, capable, and strong. These words all imply that the actions or outcomes are significant and positive. A process or person that is capable, for example, can be relied upon to accomplish their goals efficiently. Someone or something that is powerful is likely to produce a positive impact and effect in their domain. Efforts that bear fruit are successful, and they are often designed to be productive and efficient. The primary antonyms for 'in-effective' all represent qualities we hope for in the things that matter to us.