Definition of blister. 1  1 : a fluid-filled elevation of the epidermis â compare water blister. 2  2 : an enclosed raised spot (as in paint) resembling a blister. 3  3 : an agent (such as lewisite) that causes blistering. 4  4 : a fungal disease of plants marked by raised patches on the leaves.
One acre equals 0.0015625 square miles, 4,840 square yards, 43,560 square feet or about 4,047 square metres (0.405 hectares) (see below). While all modern variants of the acre contain 4,840 square yards, there are alternative definitions of a yard, so the exact size of an acre depends on which yard it is based.
According to google, 1 acre is the equivalent of 43560 square feet. 1 acre is defined to be 1 chain (66 ft) by 1 furlong (660 ft). So an acre is 66 ft * 660 ft = 43560 sq ft. The international definition is exactly the same area, but in square meters: 4046.8564224 sq m.