efficient

Everyday

1. Working well without wasting time, energy, money or materials, as in «an efficient way to tidy up». tree →
2. (of a person) Good at organising work and getting it done quickly and well. tree →
3. (science) Turning most of the energy put in into useful energy, as in «an energy-efficient light bulb». tree →

In the lessons

In science, an efficient machine wastes little energy as heat or sound; LED bulbs are more efficient than old bulbs. In maths, an «efficient method» gets the answer in fewer steps, like using times tables instead of counting. In everyday life, adults praise an «efficient» person who gets jobs done. Phrases: «energy-efficient», «fuel-efficient».

Examples

• LED bulbs are more efficient than old bulbs. tree →
• Chunking is an efficient way to divide big numbers. tree →
• Our new school secretary is very efficient. tree →
• An efficient car uses less fuel. tree →
• We worked efficiently and finished the poster early. tree →
• Recycling is an efficient use of materials. tree →

Note

Spelling: «effi-cient», with «-cient» like «ancient». Opposite: «inefficient». Do not confuse with «effective» (it works) — something can work well but slowly, so it is effective but not efficient. In science, efficiency = useful energy out ÷ total energy in, never more than 100%.