Main Entry: ar·pent Pronunciation: är-'pän Function: noun Inflected Form(s): plural ar·pents /-'pän(z)/ Etymology: Middle French Date: 1580 1 : any of various old French units of land area; especially : one used in French sections of Canada and the U.S. equal to about 0.85 acre (0.34 hectare) 2 : a unit of length equal to one side of a square arpent