Merriam-Webster Collegiate Dictionary - economy

 I. noun  (plural -mies)  Etymology: Middle French yconomie, from Medieval Latin oeconomia, from Greek oikonomia, from oikonomos household manager, from oikos house + nemein to manage — more at vicinity, nimble  Date: 15th century  1. archaic the management of household or private affairs and especially expenses  2.  a. thrifty and efficient use of material resources ; frugality in expenditures; also an instance or a means of economizing ; saving  b. efficient and concise use of nonmaterial resources (as effort, language, or motion)  3.  a. the arrangement or mode of operation of something ; organization  b. a system especially of interaction and exchange an ~ of information  4. the structure or conditions of economic life in a country, area, or period; also an economic system  II. adjective  Date: circa 1906 designed to save money ~ cars