Among its synonyms are the familiar adjectives effective and efficient. Efficacious is more formal than either of these; it’s often encountered in medical writing where it describes treatments, …

EFFICACIOUS definition: capable of having the desired result or effect; effective as a means, measure, remedy, etc.. See examples of efficacious used in a sentence.

EFFICACIOUS definition: 1. able to produce the intended result: 2. (used about a treatment or drug) working well under…. Learn more.

Capable of or successful in producing an intended result; effective as a means, remedy, etc.... Click for English pronunciations, examples sentences, video.

Definition of efficacious adjective in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

efficacious (ˌɛfɪˈkeɪʃəs) adj capable of or successful in producing an intended result; effective as a means, remedy, etc [C16: from Latin efficāx powerful, efficient, from efficere to achieve; see …

Dec 14, 2025 · Adjective efficacious (comparative more efficacious, superlative most efficacious) (formal) Effective; possessing efficacy. [from 1520s] Synonym: effective Antonym: …

When you really want to do something right, really nail it, really get at what you were going for — you're trying to be efficacious, or produce the effect you intended.

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Definition of efficacious. English dictionary and integrated thesaurus for learners, writers, teachers, and students with advanced, intermediate, and beginner levels.