Abbr. a. or ac. A unit of area in the U.S. Customary System, used in land and sea floor measurement and equal to 160 square rods, 4,840 square yards, or 43,560 square feet. See Table at measurement.
acres Property in the form of land; estate.
A wide expanse, as of land or other matter. Often used in the plural: "Everything was streaky pink marble and acres of textureless carpeting"(Anne Tyler).
Archaic A field or plot of arable land.
[Middle English aker, field, acre, from Old English æcer; see agro- in Indo-European roots.]
(ā'kər) 