What does efficiency mean?
Efficiency is the quality of achieving a desired outcome while wasting as little time, effort, money, or material as possible. A machine, process, or person described as efficient produces good results without unnecessary expenditure of resources. In physics and engineering, the word takes on a precise technical meaning: the ratio of useful output to total input, typically expressed as a percentage — no engine converts all its fuel energy into motion, so every engine has an efficiency below one hundred percent. In ordinary usage, efficiency is almost always complimentary, suggesting competence, organization, and sound management; businesses speak of cost efficiencies and governments of operational efficiency. Its opposite, inefficiency, signals waste or poor performance. Derived from the Latin efficere, meaning 'to accomplish,' the word entered English in the seventeenth century and has since become central to economics, engineering, and everyday praise of capable people.
nounThe quality or degree of achieving a desired result with minimal waste of time, effort, or resources. In physics and engineering, the ratio of useful output to total input, expressed as a percentage.
- The state or quality of being efficient; achieving maximum productivity with minimum wasted effort or expense.
- In science and engineering, the ratio of useful work performed to the total energy expended, usually expressed as a percentage.
- (dated) The production of an effect or result; effective operation (as in older philosophical usage).
"The new scheduling system dramatically improved the efficiency of our delivery routes."
"Insulating the house improved its energy efficiency and cut heating bills by a third."
"She was praised for the quiet efficiency with which she ran the entire office."
Rare compared with the uncountable form; used chiefly in business and economic writing to refer to individual measures, gains, or savings rather than the general quality.
"The merger delivered significant cost efficiencies across both companies."
The word 'efficiency' comes from Latin efficere — 'to bring about' — making it, quite literally, the art of getting things done.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of efficiency
Efficiency derives from the Latin efficientia, from efficiens ('accomplishing, bringing about'), the present participle of efficere — 'to produce, to bring about' — formed from ex- ('out') + facere ('to make or do'). It entered English in the early seventeenth century, initially carrying the philosophical sense of producing effects, before acquiring its modern emphasis on productive power without waste in the eighteenth and nineteenth centuries, particularly as physics formalized notions of mechanical work. It shares this facere root with words such as efficacy, coefficient, and effect.
Related word forms
How efficiency is actually used
Efficiency is an uncountable noun in most contexts, though it can take the plural 'efficiencies' when referring to distinct measures, savings, or improvements (e.g., 'cost efficiencies'). It carries a broadly positive connotation in everyday use, implying competence and economy, though critics sometimes associate an obsession with efficiency with coldness or short-termism.
Easily confused with efficiency
Efficacy refers to how well something produces its intended result, while efficiency emphasizes doing so with minimal wasted time, effort, or resources.