successful or achieving the results that you want: 2. (used about a treatment or drug) working…. The adjective effective describes things that are adequate to accomplish a purpose, or that produce the intended or expected result. But effective isn’t quite the same as effectual, efficacious, or efficient! Definition of effective adjective in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more. Effective and efficient are often confused, but they have slightly different meanings. If you are effective, you do a job properly; if you are efficient, you do it quickly and easily. Apr 26, 2026 · Adjective effective (comparative more effective, superlative most effective) Having the power to produce a required effect or effects. Effective means having a particular role or result in practice, though not officially or in theory. They have had effective control of the area since the security forces left. Effective, effectual, efficacious, efficient refer to that which is able to produce a (desired) effect. Effective refers to successfully producing a desired or intended result, functioning efficiently or adequately, or having an intended or expected outcome. It emphasizes the capability of producing a ….
