Each point of the quadrangle (the point where 2 sides meet) should have a letter on it. For example: A, B, C, and D. If this is the case, then the quadrangle can be named in the following four ways: ABCD BCDA CDAB DABC That should be what you are searching for. Good luck!
A quadrangle is any shape which has 4 angles. In order for an angle to exist, there needs to be two lines meeting at a point. If the shape is a polygon (a closed 2d shape) then 4 angles means it must also have 4 sides. Thus a quadrangle with only one side would be impossible.