different between efficient vs efficacious

English

Etymology

1398, “making,” from Old French, from Latin efficientem, nominative effici?ns, participle of efficere (“work out, accomplish”) (see effect). Meaning “productive, skilled” is from 1787. Efficiency apartment is first recorded 1930, American English.

Pronunciation

• (Received Pronunciation) IPA^(key): /??f???nt/
• (US, Canada) IPA^(key): /??f???nt/
• Rhymes: -???nt

Adjective

efficient (comparative more efficient, superlative most efficient)

1. making good, thorough, or careful use of resources; not consuming extra. Especially, making good use of time or energy

2. expressing the proportion of consumed energy that was successfully used in a process; the ratio of useful output to total input

3. causing effects, producing results; bringing into being; initiating change (rare except in philosophical and legal expression efficient cause = causative factor or agent)

   • It was well said of Plotinus, that the stars were significant, but not efficient.

4. (proscribed, old use) effective
   • 1801, Robert Southey, Thalaba the Destroyer:

     Ye wake no more to anguish;? ye have borne
     The Chosen, the Destroyer!? soon his hand
     Shall strike the efficient blow;
     Soon shaking off your penal forms, shall ye,
     With songs of joy, amid the Eden groves,
     Hymn the Deliverer’s praise!

   • 1856, William Dexter Wilson, An Elementary Treatise on Logic

     The Efficient Cause is that from which emanates the force that produces the Effect

Usage notes

Webster's Revised Unabridged Dictionary from 1913 still lists efficient and effective as synonyms, but all major dictionaries now show that these words now only have different meanings in careful use. Use of both for the other meaning is however widespread enough that Longman's Exam Dictionary, for example, finds it necessary to proscribe the use of one for the other with several examples at each entry and provides the following summary:

• efficient (“working quickly and without waste”)
• effective (“having the desired effect”)

Antonyms

• inefficient

Derived terms

Related terms

Translations

Noun

efficient (plural efficients)

1. (obsolete) a cause; something that causes an effect
   • 1643, Thomas Browne, Religio Medici, I.14:

     Some are without efficient, as God; others without matter, as Angels […].

   • a. 1758, Jonathan Edwards, Dissertation on Liberty and Necessity

     This implies, that something happens without a cause. If it should be said, that motive in this case is not the efficient of the action or doing — this is granted; but at the same time, for reasons already given, it is denied, that the man himself is the efficient cause of it.

References

Danish

Adjective

efficient

1. This term needs a translation to English. Please help out and add a translation, then remove the text {{rfdef}}.

Inflection

Further reading

• “efficient” in Den Danske Ordbog

French

Etymology

From Latin effici?ns.

Pronunciation

• IPA^(key): /e.fi.sj??/
• Homophone: efficients

Adjective

efficient (feminine singular efficiente, masculine plural efficients, feminine plural efficientes)

1. efficient
2. effective

Related terms

• efficience

Further reading

• “efficient” in Trésor de la langue française informatisé (The Digitized Treasury of the French Language).

Latin

Pronunciation

• (Classical) IPA^(key): /ef?fi.ki.ent/, [?f?f?ki?n?t?]
• (Ecclesiastical) IPA^(key): /ef?fi.t??i.ent/, [?f?fi?t??i?n?t?]

Verb

efficient

1. third-person plural future active indicative of effici?

English

Etymology

From Old French efficacieux, from Latin effic?x (“efficacious”) +? -ous, from efficere (“to effect, to accomplish”); see effect.

Pronunciation

• IPA^(key): /?f.?.?ke?.??s/

  Rhymes: -e???s

Adjective

efficacious (comparative more efficacious, superlative most efficacious)

1. (formal) Effective; possessing efficacy. [from 1520s]

   Synonym: effective

   Antonym: inefficacious

Related terms

Translations

Further reading

• efficacious in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913.
• efficacious in The Century Dictionary, New York, N.Y.: The Century Co., 1911.
• “efficacious”, in Lexico, Dictionary.com; Oxford University Press, 2019–present.