transitive. To make (a path, way, etc.) straight (only in figurative contexts). Also with out. Cf. right side, n. 5. Obsolete.

In a large number of phraseological expressions (often equivalent to a single verb), in which set acquires the sense of: To cause to be or become…

on (also upon) the square. to set onor upon the square, to set or put right, or in proper order. rare.