Efficient and Efficiency

adjective

• Being effective without wasting time or effort or expense.
  • usage: "an efficient production manager"; "efficient engines save gas"
• Able to accomplish a purpose; functioning effectively.
  • usage: "people who will do nothing unless they get something out of it for themselves are often highly effective persons...-G. B. Shaw; "effective personnel"; "an efficient secretary"; "the efficient cause of the revolution"
  • synonyms: effective

• (n.) Causing effects; producing results; that makes the effect to be what it is; actively operative; not inactive, slack or incapable; characterized by energetic and useful activity; as, an efficient officer, power.
• (n.) An efficient cause; a prime mover.

noun

• The ratio of the output to the input of any system.
• Skillfulness in avoiding wasted time and effort.
  • usage: "she did the work with great efficiency"

• (n.) The quality of being efficient or producing an effect or effects; efficient power; effectual agency.
• (n.) The ratio of useful work to energy expended.

Efficiency is the degree and speed with which a market accurately incorporates information into prices.