(a.) Having a valence of four; tetratomic; quadrivalent.

aboveboard authentic biquadratic bona fide cube-shaped cubed cubic cubiform cuboid diced fair and square four four-legged four-rayed genuine good-faith oblong on the level on the square on the up-and-up open open and aboveboard orthogonal quadrangular quadrate quadratic quadric quadriform quadrilateral quadrinomial quadrivalent quadruped quartic quartile quaternary rectangular rhombic rhomboid single-hearted square square-dealing square-shooting straight straight-shooting tetractinal tetrad tetragonal tetrahedral tetravalent trapezohedral trapezoid up-and-up veritable