Don't confuse "efficacy" with "efficiency".
Source: tatoeba (538449)
Efficacy
/ˈɛf.ɪ.kə.si/
Synonyms for "efficacy" (47 found)
Ranked by relevance and common usage.
Closest matches (10)
Strong matches (14)
Noun(3 words)
Adjective(1 words)
operational capability
Verb(1 words)
perform a task
Related words (23)
Noun(7 words)
Verb(2 words)
produce resultsprove usefulness
Adjective(1 words)
yielding capacity
Choosing the right synonym
- Closest matches in this entry: ability, availability, caliber, capability, capacity.
- Sentence evidence is available for efficacy, so synonym choice can be checked against real usage rather than a flat word list.
- Ranking signals come from derived_reverse, opengloss, wordnet, wiktionary, and related lexical sources.
Synonym selection checklist
- Match the part of speech before comparing meanings.
- Check whether the synonym changes intensity, formality, or emotional tone.
- Read the replacement inside the full sentence, not just beside "efficacy".
- Prefer the clearest word over the most unusual word when writing for speed or comprehension.
When not to replace "efficacy"
Keep "efficacy" when the sentence already sounds natural, when a synonym would add unintended emphasis, or when readers need the most familiar wording. A synonym should clarify or sharpen the message, not simply make the sentence look more varied.
If two options seem close, choose the one that best matches the audience and purpose of the sentence.
Replacement workflow
1. Preserve meaning
Choose a synonym only if it keeps the core idea of "efficacy" intact in the sentence you are editing.
2. Tune tone
Check whether the replacement sounds more formal, casual, emotional, technical, or forceful than the original word.
3. Re-read context
Read the full sentence after the swap. Keep the synonym only when the sentence becomes clearer or more precise.
Review note: Synonym lists are ranked with lexical data and reviewed for practical writing value. Use the comparison notes, sentence evidence, and source labels together; a high-ranking synonym can still be wrong when the audience, register, or grammar changes.
Final fit check
After choosing a replacement for "efficacy", read the sentence once for meaning and once for rhythm. The best synonym should feel natural in the full sentence, not only accurate in a word list.
If the synonym makes the sentence slower, vaguer, or more dramatic than intended, keep "efficacy" or choose a simpler alternative from the closest-match group.
Related word relations
OpenGloss and ConceptNet supply richer edges like generalizations, collocations, and derivations.
More general
4 entriesMore specific
3 entriesclinical efficacydrug efficacytreatment efficacy
Collocations
6 entriesclinical efficacydrug efficacyincrease efficacymeasure efficacyoverall efficacyperceived efficacy
Inflections
1 entriesDerivations
3 entriesAntonyms
1 entriesTranslations
44 translations across 26 languages.
Ancient Greek
1 entries- δρᾶσις noun (ability to produce effect)
Azerbaijani
2 entries- səmərə noun (ability to produce effect)
- təsirlilik noun (ability to produce effect)
Bulgarian
1 entries- де́йственост noun (ability to produce effect)
Catalan
1 entries- eficàcia noun (ability to produce effect)
Chinese Mandarin
4 entries- 功效 noun (ability to produce effect)
- 效力 noun (ability to produce effect)
- 效能 noun (ability to produce effect)
- 效驗 /效验 noun (ability to produce effect)
Czech
2 entries- efektivnost noun (ability to produce effect)
- účinnost noun (ability to produce effect)
Dutch
1 entries- doeltreffendheid noun (ability to produce effect)
Esperanto
1 entries- efikeco noun (ability to produce effect)
Finnish
1 entries- tehokkuus noun (ability to produce effect)
French
2 entries- efficacité noun (ability to produce effect)
- efficience noun (ability to produce effect)
German
4 entries- Wirkfähigkeit noun (ability to produce effect)
- Wirksamkeit noun (ability to produce effect)
- Wirkungsfähigkeit noun (ability to produce effect)
- Wirkungsvermögen noun (ability to produce effect)
Hungarian
1 entries- hatékonyság noun (ability to produce effect)
Indonesian
4 entries- efikasi noun (ability to produce effect)
- keampuhan noun (ability to produce effect)
- kemanjuran noun (ability to produce effect)
- khasiat noun (ability to produce effect)
Interlingua
1 entries- efficacia noun (ability to produce effect)
Italian
1 entries- efficacia noun (ability to produce effect)
Japanese
1 entries- 有効性 noun (ability to produce effect)
Latin
1 entries- efficacitas noun (ability to produce effect)
Polish
2 entries- efektywność noun (ability to produce effect)
- skuteczność noun (ability to produce effect)
Portuguese
1 entries- eficácia noun (ability to produce effect)
Romanian
1 entries- eficacitate noun (ability to produce effect)
Russian
2 entries- де́йственность noun (ability to produce effect)
- эффекти́вность noun (ability to produce effect)
Slovak
1 entries- efektívnosť noun (ability to produce effect)
Slovene
1 entries- učinkovitost noun (ability to produce effect)
Spanish
1 entries- eficacia noun (ability to produce effect)
Swedish
1 entries- effektivitet noun (ability to produce effect)
Ukrainian
2 entries- діє́вість noun (ability to produce effect)
- ефекти́вність noun (ability to produce effect)
Sample sentences
14 total sentences available.
The aim of this study was to evaluate the efficacy of acupuncture in the treatment of SAR through a randomized controlled trail.
Source: tatoeba (4264776)
This practice is of dubious efficacy.
Source: tatoeba (6049469)
Testing a vaccine for safety and efficacy will take 12 to 18 months or more.
Source: tatoeba (8592362)
Showing 4 of 14 available sentences.
Common questions
What are the closest synonyms for "efficacy"?
Closest matches include ability, availability, caliber, capability, capacity.
How should I check whether a synonym fits "efficacy"?
Compare the replacement against real sentence context. This entry includes sample sentences so you can check tone, grammar, and meaning before swapping words.