Economic Definition of efficient. Defined.
Offline Version: PDF
Term efficient Definition: The state of resource allocation the exists when the highest level of consumer satisfaction is achieved from the available resources. Competitive markets, absent of any market failure and especially market control by either side, is efficient. In particular, this feat is accomplished when the price buyers are willing and able to pay for a good--based on the satisfaction obtained--is equal to the price sellers need to charge for a good--based on the opportunity cost of production. In other words, the value (satisfaction) of stuff given up to get a good is the same as the value (satisfaction) of the good produced. Satisfaction won't increase by producing more of either.