Ark (from Lat. area, a broad piece of level ground), the unit of surface in the French system of measures, equivalent to a square decametre, or 1,076.44 English square feet. Parts of an are are expressed by Latin prefixes, declare, centiare, etc., signifying one tenth, one hundredth, etc, of an are. Multiples of an are have Greek prefixes, decare, hectare, etc, signifying ten, one hundred, etc., ares.