1530s, "household management," from Latin oeconomia, from Greek oikonomia "household management, thrift," from oikonomos "manager, steward," from oikos "house" (cognate with Latin vicus "district," vicinus "near;" Old English wic "dwelling, village;" see villa) + nomos "managing," from nemein "manage" (see numismatics). The sense of "wealth and resources of a country" (short for political economy) is from 1650s.
as a term in advertising, at first meant simply "cheaper" (1821), then "bigger and thus cheaper per unit or amount" (1950). See economy (n.).