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.
1 acre = 43,560 square feet. To calculate the area of a room in square feet, measure the length and width of the room in feet, then multiply these figures together to give an area in ftÂ².