Is "square an compass" or "square and comapsses"?

The correct Masonic designation is "Square and Compasses" 1.

Using the singular form "compass" is an error introduced by early American Masons 1. A compass is a navigational instrument for finding directions and has never served as a Masonic symbol 1. The drafting tool used for drawing circles and measuring distances is properly called compasses 1. This mistake was perpetuated in the naming of organizations such as the Square and Compass college fraternity, established in 1917, which adopted the singular title despite the traditional usage 1.