late 14c., marchaundising, "goods, commodities, mercantile business," verbal noun from merchandize (v.). Meaning "trade, commerce" is from mid-15c. That of "promotion of goods for sale, activities meant to stimulate interest in products" is by 1910.
mercenary
mercer
merchandise
merchandize
merchandizer
merchandizing
merchant
merchantman
Mercia
merciful
merciless