To cheap was to bargain or deal. In Old English it was spelled céap. The ch spelling arose from a later rendering of the soft southern English c. The word appears in names such as Cheapside, Eastcheap and Chepstow; all markets or dealing places. Originally then, a céapmann was a trader or dealer: a merchant. By 1600, the word had come to be applied to an itinerant dealer. The habit of calling a young man a 'chap' arose from the use of the abbreviated word to mean a customer, one with whom to bargain but the complete word, chapman was still used of a customer around 1800. In the seventeenth and eighteenth centuries, the word was applied to hawkers of chapbooks, broadside ballads, and similar items. Their stock in trade provides a graphic insight into the methods of political and religious campaigners of the Civil War period, for example.
Chapman is also a common personal name of the class derived from trades.