efficient

Etymology
1398, “making,” from, from , nominative , participle of (see ). Meaning “productive, skilled” is from 1787. Efficiency apartment is first recorded 1930, American English.

Adjective

 * 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)
 * 4)  effective, efficacious
 * 1) expressing the proportion of consumed energy that was successfully used in a process; the ratio of useful output to total input
 * 2) causing effects, producing results; bringing into being; initiating change (rare except in philosophical and legal expression efficient cause = causative factor or agent)
 * 3)  effective, efficacious
 * 1)  effective, efficacious
 * 1)  effective, efficacious
 * 1)  effective, efficacious

Usage notes
Webster's Revised Unabridged Dictionary from 1913 still lists and  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:

Translations

 * Belarusian: эфекты́ўны
 * Bulgarian: ,
 * Catalan:
 * Chinese:
 * Mandarin: 高效率
 * Czech:
 * Dutch:
 * Finnish:, säästäväinen ja tehokas, taloudellinen ja tehokas
 * French:
 * German:
 * Greek:
 * Ancient: δραστικός
 * Hebrew:
 * Hungarian: ,
 * Icelandic: skilvirkur, nýtinn
 * Ido:
 * Irish: éifeachtúil, éifeachtach, feidhmiúil
 * Italian: ,
 * Korean: 효율적-인
 * Latin: efficiens
 * Malay:, efisien
 * Polish:
 * Portuguese:
 * Romanian:
 * Russian:
 * Scottish Gaelic: èifeachdach
 * Spanish: ,
 * Tagalog: episyente
 * Turkish:
 * Ukrainian: ефекти́вний


 * Bulgarian:
 * Catalan:
 * Czech:
 * Dutch:
 * Finnish:
 * French:
 * Hungarian: ,
 * Irish: éifeachtúil
 * Italian:
 * Polish:
 * Portuguese:
 * Scottish Gaelic: èifeachdach
 * Tagalog: episyente


 * Bulgarian:
 * Finnish:
 * Irish: éifeachtúil
 * Portuguese:
 * Sanskrit:
 * Spanish:

Noun

 * 1)  a cause; something that causes an effect

Derived terms

 * Pareto efficient

Etymology
.

Adjective

 * 1) effective
 * 1) effective