efficiency
/ɪˈfɪʃnsi/ (bre, ipa) · /ɪˈfɪʃnsi/ (ame, ipa) · /i-ˈfi-shən-sē/ (ame, mw)
efficiency — noun
1. how well a system, machine, or process converts resources such as energy, fuel,
how well a system, machine, or process converts resources such as energy, fuel, or time into useful output — for example, a car engine that travels further on less petrol, or a factory that makes more products using fewer materials.
The new heating system improved the factory's energy efficiency by nearly thirty percent.
collocation: energy efficiency
Faisal redesigned the delivery routes to increase fuel efficiency across the whole fleet.
collocation: fuel efficiency
The engineer measured the efficiency of solar panels on the school roof.
Ife was surprised how much the old boiler's efficiency had dropped after years of use.
Even a small gain in engine efficiency can save a firm thousands per year.
- effectiveness
Effectiveness is about achieving the intended result; efficiency is about achieving it with minimal waste.
- productivity
Productivity focuses on the amount of output per unit of input over time, while efficiency focuses on reducing waste across any resource.
- economy
Economy in this sense emphasizes saving money or resources, often in a broader financial context.
- inefficiency
The direct opposite — wasteful use of resources.
用法筆記
Commonly modified by adjectives that specify the type of resource: 'energy efficiency', 'fuel efficiency', 'cost efficiency'. The preposition 'of' introduces the system or device being measured.
常見錯誤
2. how well a person or group carries out tasks in an organised, productive manner,
how well a person or group carries out tasks in an organised, productive manner, making good use of time and avoiding wasted effort — for example, a kitchen team that serves hundreds of meals without falling behind.
The new software helped the team work with greater efficiency and far fewer delays.
preposition: with + efficiency
Lucas admired the kitchen staff's efficiency during the busy lunch service at the hotel.
Alessia runs the office with an efficiency that makes every coworker's job noticeably easier.
The manager praised her department for its efficiency in meeting every single deadline last quarter.
The emergency team's efficiency saved lives when the storm hit the coastal town.
- effectiveness
Effectiveness stresses whether a goal is achieved at all; efficiency stresses how well resources are used while achieving it.
- competence
Competence refers to having the necessary skill or ability; efficiency refers to the speed and economy with which work is done.
- proficiency
Proficiency implies advanced skill gained through practice; efficiency is more about process than skill level.
- inefficiency
The direct opposite — disorganised, time-wasting work.
- disorganisation
Disorganisation is a cause of low efficiency; the two are closely related but not synonymous.
用法筆記
Often combined with 'in' followed by a gerund or noun ('efficiency in handling complaints', 'efficiency in communication'). Can be modified by 'greater', 'higher', 'improved', or 'remarkable'.
常見錯誤
3. a specific step or practice introduced in a business or institution to cut down
a specific step or practice introduced in a business or institution to cut down on wasted resources — for example, switching off equipment overnight or ordering supplies in larger batches.
The company introduced several energy efficiencies that cut their electricity bill by almost half.
plural form: efficiencies
Obi suggested a simple efficiency — turning off the lights in unused rooms after six.
The hospital identified fifteen cost efficiencies after reviewing its supply orders for the past year.
Dewi's report listed efficiencies that could save the school fifty thousand dollars a year.
- cost-saving measure
More explicit about the financial motivation; 'efficiency' is broader and can refer to time or energy savings too.
- improvement
A general term; 'efficiency' specifically implies reducing waste rather than any kind of change.
- optimisation
Suggests a systematic, data-driven improvement to a process, whereas 'efficiency' can be a simpler practical change.
- waste
Waste is what efficiencies aim to eliminate — the opposite of a saving measure.
用法筆記
This is the only sense that is regularly used in the countable plural form ('efficiencies'). In business contexts it often appears in the phrase 'cost efficiencies' or 'operational efficiencies'.
常見錯誤
4. a calculated value, often expressed as a percentage, that compares the useful wo
a calculated value, often expressed as a percentage, that compares the useful work delivered by a machine or system with the total energy it receives — for example, a motor that converts 80 % of its electrical power into motion.
An electric car motor can reach an efficiency of over ninety percent on good roads.
pattern: an efficiency of + percentage
The engineers tested the new turbine's efficiency under different weather conditions for a month.
Ilan calculated that the water pump's efficiency had dropped below sixty percent after two years.
Solar panels typically have an efficiency between fifteen and twenty-two percent, depending on their quality.
- yield
Yield refers to the amount produced, not the ratio of output to input. A system can have high yield but low efficiency if it uses huge inputs.
- output ratio
A descriptive phrase rather than a standard synonym; 'efficiency' is the standard technical term for this ratio.
- performance
Performance is a broader term covering speed, reliability, and other factors, not just the input-output ratio.
用法筆記
This technical sense is used almost exclusively in engineering, physics, and energy-industry contexts. The noun is often modified by a percentage value following 'of'. Frequently appears in the phrase 'thermal efficiency' (heat engines), 'conversion efficiency' (solar cells), or 'mechanical efficiency' (machinery).
5. a small apartment or flat where the sleeping, living, and cooking areas are all
a small apartment or flat where the sleeping, living, and cooking areas are all in a single large space, with only the bathroom separated — especially common in American English, where the full term is 'efficiency apartment'.
Felix rented a small efficiency near the university for his first year of graduate school.
US English: efficiency (apartment)
The building on Maple Street has twelve efficiencies and three larger one-bedroom units for families.
Defne found an efficiency whose large windows made the small space bright and open.
Rents for efficiencies in the downtown area have risen fifteen percent over two years.
- studio apartment
The more common term in both American and British English; 'efficiency' is slightly older and more common in real-estate listings.
- studio flat
The British equivalent term.
- bedsit
A British term for a single room used as both bedroom and living room, usually with shared bathroom facilities — different from an efficiency which has a private bathroom.
用法筆記
Chiefly used in American English. In British English the equivalent is 'studio flat' or 'studio apartment'. The full form 'efficiency apartment' is also common in real-estate listings. This sense is always countable.