The condition of being tetragonal.

In a tetragonal manner

Having four sides, like a tetragon. / (crystallography) Having two equal axes and one unequal, and all angles 90°.

(geometry, rare) Quadrilateral. / An aspect of two planets with regard to the Earth when they are distant from each other ninety degrees, or a quarter-circle.

plural of tetragon

(chiefly botany) tetragonal

(dated, mathematics) quadrature of the circle