The tetrad for the perfect figure—the cube, length, depth, and width.
Having sent for that Brhman, he learnt from him a tetrad of gths.
They are aborting members of the tetrad, and appear to have been used as food by the other spores.
Such an axis of symmetry is known as a tetrad axis of symmetry.
If the second cell division plane is formed at right angles to the first, a ...