square
A four-sided building plan with right-angle corners and side lengths differing by no more than 5% of the shortest side.
A square perimeter is a building plan with four even sides which meet at 90 degree angles. The lengths of all sides should not be recognizably different, and should therefore be identical within 5% of the shortest length.
Squares can have shallow indentations in the sides, or may have slightly chamfered corners. Buildings with square plans very often have light courts or other courtyards in the middle because of the high area-to-perimeter ratio.
The comparison concerns the principal side lengths, while shallow notches and slight corner chamfers can remain. A rectangle has a discernibly longer axis; a central court does not by itself change the square outer outline.
