No. It is not a square. Clearly this quadrilateral does not match all of the critera needed to fit the image/idea of a square. Although all of the vertices are 90 degree angles and the polygon is indeed a quadrilateral, the sides of the figure are not all the same length. That image is not one of squarish preportions. Therfore, it is not a square.
P.S. I tried to add in mathmatic words. Im not that much of a knowitall. Hope they get u an A+!!!