The gathering together of people for the purposes of trade, thus the licence of a lord to hold such an event from which he made money. On market days all shops within a set radius were required to be shut so that there was no competition. The Latin phrase used for a market in the records was venalis locus = a place for selling. [< Lat. mercatum = a meeting for trade, a fair or market]
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.