efficiency
- 01 B2 Upper Intermediate
the ability to do something well and quickly without wasting time, money, or energy.
the state or quality of being efficient; the ability to achieve maximum productivity with minimum wasted effort or expense.
Simple“The new heating system has much better energy efficiency than the old one.”
In context“The consultancy firm was hired to improve the operational efficiency of the factory by streamlining the assembly line process.”
UsageOften used with the preposition 'of' when referring to a specific resource, such as 'efficiency of fuel'.
SynonymsAntonymsinefficiencywastefulness - 02 C1 Advanced
the ratio of useful work or energy produced compared to the energy put in.
the ratio of the useful work performed by a machine or in a process to the total energy expended or heat taken in.
Simple“Most car engines have a thermal efficiency of only about twenty-five percent.”
In context“Engineers are constantly seeking to increase the aerodynamic efficiency of the aircraft to reduce fuel consumption during long-haul flights.”
UsageUsually expressed as a percentage or a decimal between 0 and 1.
- 03 C1 Advanced
a small apartment that usually has only one main room for living and sleeping.
a small, self-contained apartment, typically consisting of a single main room with a small kitchen area and a bathroom.
Simple“He rented a small efficiency near the university to save money on rent.”
In context“The building offers several efficiencies that are ideal for single professionals who prioritize a central location over square footage.”
UsageCommonly used in real estate listings in the United States.
Teacher's tipLearners should note that 'studio apartment' is more common globally, while 'efficiency' is specifically American.
Synonymsstudiobedsitter - 04 C2 Proficiency
the power or ability to produce a specific result.
the capacity or power to produce a desired effect or result.
Simple“The old books spoke of the efficiency of certain herbs in curing fevers.”
In context“The philosopher questioned the efficiency of the law in truly changing human behaviour rather than merely punishing it.”
UsageIn modern English, 'efficacy' is almost always preferred for this meaning.
Teacher's tipThis sense is rarely encountered in modern speech; advise students to use 'efficacy' for the power of a medicine or treatment.
Usage efficiency standards · efficiency across the estate · efficiency of our existing
“EPCs are documents that provide an energy efficiency score for properties, in relation to their running costs.”
“It is an argument for measuring food security, livelihoods and climate outcomes together rather than assuming that improved efficiency guarantees an absolute reduction in greenhouse gas emissions from livestock.”
From Latin efficientia, equivalent to efficient + -cy.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.