n. Originallyn. A superficial measure of land, usually stated to be 40 poles in length by 4 in breadth; but 160 perches (= 4840 square yards, or 43,560 square feet) make an acre, however shaped.n. A lineal measure equal to a furrow's length, or 40 poles; more frequently, an acre's breadth, 4 poles, equal to 22 or 25 yards.