efficacious - Master This Word
Master this word with our 5-step learning method – Learn English in English
efficacious Word Meanings
- capable of producing desired results
- effective in achieving goals
- having the power to produce a specific effect
efficacious Example Sentences
Example sentences are the start of understanding. Don't rush to memorize. First feel how the word works in a sentence.
efficacious Phonetic & Pronunciation
UK
/ˌɛfɪˈkeɪʃəs/
US
/ˌɛfɪˈkeɪʃəs/
efficacious Word Etymology
efficacious: ex- = out + facere = to do/make; Latin → Old French → English. Imagine a medicine doing its job, bringing health and relief outward from the body.
Note 1: These definitions and etymologies are not standard dictionary definitions, but extended explanations provided to help with memorization and understanding of the actual application of words. Through this background information, we strive to make words more vivid and easier to understand, and help you remember their meanings in real life.
Note 2: LexiTalk designs the learning flow around the linguistics principle of “Comprehensible Input.” When learners encounter material that is slightly above their level but still understandable from context, the brain naturally absorbs the language. That’s why we keep every word inside authentic contexts, using examples and associations to help you understand it and use it flexibly.
Read the FAQ explanation of Comprehensible InputReal Context
Efficacious is a formal adjective meaning capable of producing the desired result. It is commonly used in medicine, policy, and academic writing to emphasize an inherent capacity to cause a specific effect, not just being good in practice. Learners often mix it up with effective; effective describes what actually works for real people in real life, while efficacious focuses on potential or the promise of producing the effect under proper conditions. Typical collocations include efficacious remedy, efficacious treatment, and an efficacious intervention. Its Latin-rooted feel contrasts with more everyday synonyms, yet it remains relatively rare in casual speech. Example: The drug proved efficacious in clinical trials.
Usage Reminders
- Distinguish efficacious from effective; note formal register and medical contexts; practice collocations; pronounce with stress on -cious; don’t overuse in casual speech; compare with efficient for nuance.
Common Misconceptions
- It simply means 'effective' in all contexts.
- It can replace 'efficient' in every situation.
- If a drug is efficacious, it always works in real life.
- Efficacious and efficacy are interchangeable as adjectives.
- You should use it in casual conversations with friends.
Thinking Differences
In English, efficacious signals a formal, outcome-focused assessment, often technical or academic, and may imply trial conditions or theoretical potential rather than everyday use. Learners tend to overgeneralize it as simply 'effective' and may misplace it in casual conversation.
Learning Tips
- Learn the formal register and typical medical or policy contexts.
- Differentiate efficacious (potential/ability) from effective (actual result).
- Memorize common collocations: efficacious remedy, efficacious treatment.
- Pronounce with stress on the second syllable: /ˌɛfɪˈkeɪʃəs/.
- Compare with efficient to avoid mixing up outcomes with speed or resources.
- Practice with clinical trial sentences to reinforce context.
5-Step Learning Method - Learn English in English
Step 1: Meaning
What is the meaning of 'efficacious'?
A.Broken
B.Busy
C.Sad
D.Effective
Step 2: Usage
In which of the following sentences is 'efficacious' used correctly?
A.She was inefficacious in solving the problem.
B.His inefficacious efforts led to success.
C.The medicine proved to be efficacious in treating the illness.
D.The inefficacious plan was a huge success.
Step 3: Similar Words
Which word is a synonym of 'efficacious'?
A.Powerful
B.Ineffective
C.Useless
D.Inefficient
Step 4: Opposite Words
Which word is an antonym of 'efficacious'?
A.Ineffective
B.Powerful
C.Useful
D.Effective
Step 5: Mastery
In what real-life context would you use the word 'efficacious'?
A.Discussing a fun activity
B.Describing a strong medication for a disease
C.Referring to a broken machine
D.Talking about a lazy person
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