efficient

Pluralefficients

1. 1
   adjective

   Making good and careful use of time, energy, or resources without consuming any extra.

   Like an engine that turns nearly all its fuel into motion, with little lost as heat.

   The factory adopted more efficient methods to cut energy use.

   An efficient team finishes the project with very little wasted effort.

   Similareconomical, productive, streamlined, organized, effective

   Oppositeinefficient, wasteful, disorganized, unproductive

   Note

   The everyday sense is the youngest. Efficient entered English in 1398 meaning "making," from Latin efficere, "work out, accomplish," and the meaning "productive, skilled" arrives only in 1787. It grades freely, from more efficient methods to cleaners who are almost too efficient. It applies equally to people, processes and machines, and it always carries the idea that nothing is spent for nothing.

2. 2
   adjective

   Expressing the share of consumed energy that does useful work; the ratio of useful output to total energy input.

   The engine converts fuel to motion at an efficient rate, wasting little as heat.

   Newer turbines are far more efficient than models from a decade ago.

   Similareconomical

   Oppositeinefficient, wasteful

   Note

   Here the word becomes a measurement. An engineer can call a motor only 20% efficient, putting a percentage directly in front of the adjective, a construction the everyday sense never takes. The figure is the share of the input that comes out as useful work, and whatever is left over is lost, so the scale tops out at 100%.

3. 3
   adjective

   Causing effects or bringing something into being; producing a result, now rare outside the philosophical and legal phrase efficient cause.

   In Aristotle's framework, the sculptor is the efficient cause of the finished statue.

   The court identified the faulty wiring as the efficient cause of the fire.

   Note

   What is efficient in this sense does something rather than saves something. It is the old "making" meaning that the everyday sense grew away from. It survives mainly in the phrase efficient cause, used in philosophy and in law, where it pairs naturally with direct: the direct and efficient cause of an injury. Walter Raleigh's The Historie of the World (1614) sets it against significant: the stars signify, but they do not act.

4. 4
   adjectivenonstandard

   Producing the intended effect; effective or efficacious.

   The physician prescribed a remedy he deemed efficient against the fever.

   They sought an efficient cure for the ailing crops.

   Similareffective, efficacious, effectual, potent

   Oppositeineffective, ineffectual, useless

   Note

   Careful usage now marks this meaning as an error: efficient used for simple success, with no thought of economy. Robert Southey's Thalaba the Destroyer (1801) has a hand that "shall strike the efficient blow," meaning a blow that does its work. The trap is that both words describe success. Where saving effort plays no part, the word wanted today is effective or efficacious.

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