4 syllables: Ef, fi, ca, cy. Stress on Ef.
EF-ik-as-ee
/ˈɛfɪˌkæsi/
Efficacy is pronounced EF-ik-as-ee (/ˈɛfɪˌkæsi/). It has four syllables (Ef-fi-ca-cy), with the stress on "Ef". Efficacy refers to the ability to produce a desired or intended result. As a noun, it is used to describe how effective something is, especially in clinical or evaluative contexts. The term emphasizes actual outcome over intention, reliability, or theoretical potential, and is common in medicine, policy, and research discussions.
nounEfficacy refers to the ability to produce a desired or intended result. As a noun, it is used to describe how effective something is, especially in clinical or evaluative contexts. The term emphasizes actual outcome over intention, reliability, or theoretical potential, and is common in medicine, policy, and research discussions.
"The study measured the drug's efficacy in reducing symptoms."
"We evaluated the efficacy of the new teaching method over a semester."
"Regulators require evidence of efficacy before approval."
Pronounce as /ˈef.ɪ.kə.si/ in US/UK/AU. The syllables are EF-uh-KUH-see, with primary stress on the first syllable. Start with a clear ‘eh’ as in ‘bed,’ then a quick, lighter ‘fi’ sound, followed by a schwa in the third syllable and a crisp final /si/ as in ‘see.’ Ensure the second syllable receives less stress than the first. Audio reference: many dictionaries mark /ˈef.ɪ.kə.si/ and you can hear it on Pronounce or Cambridge audio.
Common errors include reducing the first syllable too much (e.g., /ˈefɪkəsi/ with a weak first vowel), or slurring the middle syllable into the second (e.g., /ˈefiˌkəsi/). Another frequent miss is mispronouncing the final /si/ as /sɪ/ or /siː/ instead of /si/. Focus on keeping the /æ/ or /e/ quality short in the first vowel and clearly articulating the /si/ at the end. Practice with the full /ˈef.ɪ.kə.si/ to maintain the rhythm and avoid vowel reduction in stressed syllables.
In US, UK, and AU, the pronunciation is largely similar with a stressed first syllable /ˈef.ɪ.kə.si/. Differences are subtle: US speakers may have a slightly reduced middle vowel to a more centralized /ə/, UK and AU may emphasize the second syllable slightly more, giving a marginally crisper /kə/ before /si/. Rhoticity affects only connected speech; the word itself is non-rhotic when followed by a consonant in British speech. Listen for minor vowel quality shifts rather than a different syllable count.
Two main challenges: the middle syllable with a schwa plus a light /k/ before the final /si/ can slide, creating an indistinct /kə/ if you’re not precise. The sequence /ɪ.kə/ requires quick but clear transition from a near-close front vowel /ɪ/ to a mid-central /ə/. Some speakers also over-soften the final /si/, making it /siː/ or /si/ unsounded. Practice slowing to slow-medium tempo, then speed up, ensuring each consonant is crisp and the final /si/ lands clearly.
Efficacy ends with an unstressed, crisp final /si/ that can blur in fast speech if you drop the /i/ vowel sound. A unique aspect is maintaining the separating schwa in the third syllable: /ˈef.ɪ.kə.si/. If you drop the /ə/ you tilt toward /ˈef.ɪksi/ which is incorrect. Keep the middle syllable stable, and ensure the final /si/ isn’t devoiced or lengthened. Use a speed ladder to lock the final /si/ cleanly.
🗣️ Voice search tip: These questions are optimized for voice search. Try asking your voice assistant any of these questions about "Efficacy"!
Efficacy comes from the Latin efficacia, from efficax, meaning ‘effective, bringing about.’ The Latin root effic- is from efficere, meaning ‘to bring about, accomplish.’ In early medical and philosophical Latin, efficacia described the power to produce a desired effect. The word entered English via late Latin and Old French, gradually adopting a more specialized meaning in medicine and public policy by the 16th–18th centuries. Its usage expanded with the rise of clinical trials, pharmacology, and evidence-based practice, where measuring efficacy became essential. Throughout modern English, efficacy has retained a formal tone, often co-occurring with terms like medical, therapeutic, statistical, or demonstrable. First known uses appear in scholarly and legal texts in the 16th–17th centuries, with a notable rise in the 19th and 20th centuries as experimental methods matured. Today, efficacy is a benchmark concept in evaluating interventions, services, and products, distinct from efficiency or effectiveness by focusing on the ability to produce the intended result under controlled or specified conditions.
💡 Etymology tip: Understanding word origins can help you remember pronunciation patterns and recognize related words in the same language family.
Help others use "Efficacy" correctly by contributing grammar tips, common mistakes, and context guidance.
💡 These words have similar meanings to "Efficacy" and can often be used interchangeably.
🔄 These words have opposite meanings to "Efficacy" and show contrast in usage.
📚 Vocabulary tip: Learning synonyms and antonyms helps you understand nuanced differences in meaning and improves your word choice in speaking and writing.
Words that rhyme with "Efficacy"
-acy sounds
-ncy sounds
Practice with these rhyming pairs to improve your pronunciation consistency:
🎵 Rhyme tip: Practicing with rhyming words helps you master similar sound patterns and improves your overall pronunciation accuracy.
