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See also: efficiënt



1398, “making,” from Old French, from Latin efficientem, nominative efficiēns, participle of efficere (work out, accomplish) (see effect). Meaning “productive, skilled” is from 1787. Efficiency apartment is first recorded 1930, American English. [1]



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.
    • 2013 June 1, “A better waterworks”, in The Economist[1], volume 407, number 8838, page 5 (Technology Quarterly):
      An artificial kidney these days still means a refrigerator-sized dialysis machine. Such devices mimic [] real kidneys [] . But they are nothing like as efficient, and can cause bleeding, clotting and infection—not to mention inconvenience for patients, who typically need to be hooked up to one three times a week for hours at a time.
    An efficient process would automate all the routine work.
    Our cleaners are almost too efficient: they throw away anything left out on a desk.
  2. Expressing the proportion of consumed energy that was successfully used in a process; the ratio of useful output to total input.
    The motor is only 20% efficient at that temperature.
  3. Causing effects, producing results; bringing into being; initiating change. (Rare except in philosophical and legal expression efficient cause = causative factor or agent.)
    Ownership, maintenance, or use of the automobile need not be the direct and efficient cause of the injury sustained
  4. (proscribed, old use) Effective.
    • Wilson
      The efficient cause is the working cause.
Usage notes[edit]

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)


Derived terms[edit]

Related terms[edit]



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 […].
    • Jonathan Edwards
      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.


  1. ^ efficient” in Douglas Harper, Online Etymology Dictionary, 2001–2019.




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


Inflection of efficient
Positive Comparative Superlative
Common singular efficient 2
Neuter singular efficient 2
Plural efficiente 2
Definite attributive1 efficiente
1) When an adjective is applied predicatively to something definite, the corresponding "indefinite" form is used.
2) The "indefinite" superlatives may not be used attributively.

Further reading[edit]




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

  1. efficient
  2. effective




  1. third-person plural future active indicative of efficiō