(1):

(n.) A piece of land, containing 160 square rods, or 4,840 square yards, or 43,560 square feet. This is the English statute acre. That of the United States is the same. The Scotch acre was about 1.26 of the English, and the Irish 1.62 of the English.

(2):

(n.) Any field of arable or pasture land.