Ohms per Square
The resistance of any square area of thin film resistive material as measured between two parallel sides.
A unit of resistivity for surface films and other materials whose thicknesses are considered to be negligible.
The resistivity of a very thin conductor is defined to be its resistance (in ohms) multiplied by its width and divided by its length. If the conductor is square in shape, then its length and width are the same and its resistivity is simply equal to the resistance of the square. Whatever the size of the square the number will be the same.
The distance unit is lost in thi division, but convention uses Ohms per Square to describe the nature of the unit and measurement.
See also: Ohm.