A line segment connecting two nonadjacent vertices of a polygon is called a diagonal . Use the link below to verify this and gather more information.
http://wiki.answers.com/Q/A+line+segmentnot+a+side...

A line segment in a polygon connecting any 2 nonconsecutive vertices is called a diagonal.
http://wiki.answers.com/Q/A+line+segment+that+conn...
