mid-13c., "trading, commerce;" mid-14c., "commodities of commerce, wares, articles for sale or trade," from Anglo-French marchaundise, Old French marcheandise "goods, merchandise; trade, business" (12c.), from marchaunt "merchant" (see merchant).
also merchandize, "to buy and sell; to market," late 14c.; see merchant + -ize. Meaning "promote the sale of goods" is from 1926. Related: Merchandising; merchandizing.