What is "squircle"

n. 1 (context mathematics English) A closed curve having properties intermediate between those of a square and a circle 2 (context geometry English) A geometrical shape defined by the boolean intersection of a square and a concentric circle whose diameter is greater than the length of the side of the square, but less than the length of the diagonal of the square

A squircle is a mathematical shape intermediate between a square and a circle. It is a special case of a superellipse. The word "squircle" is a portmanteau of the words "square" and "circle".